This paper uses the kernel density to study the spatiotemporal distribution pattern of inscription sites in Henan Province. There are a total of 1929 sites in the study area from the Han Dynasty to the present (see
Table 1). The spatial clustering of these inscription sites is obvious, showing the distribution pattern of “one belt and four clusters”. They are mainly distributed in the northern, northwestern, southern, southwestern, eastern, and central regions of Henan Province. Among them, the northern and northwestern regions show a more obvious southwest–northeast strip clustering feature, mainly located in five cities, including Anyang and Zhengzhou, while the northern and northwestern regions are the center’s inscriptions. The spatial distribution of these sites is relatively uneven and the clustering is obvious. The density is high in the north and low in the south, gradually decreasing from north to south (
Figure 3 and
Figure 4).
In terms of time, the number of Henan inscription sites has shown a slight increase from the Han Dynasty to the Tang Dynasty, a decrease from the Five Dynasties and Ten Kingdoms period to the Jin Dynasty, a significant increase from the Yuan Dynasty to the Qing Dynasty, and a decrease from the Republic of China to the New China. The center of inscription sites has changed over time, migrating from southwest to northeast.
3.1. Clustering Characteristics of Henan Inscription Sites in Different Periods
The nearest neighbor index is used to analyze Henan inscription sites and explore their spatial distribution pattern. The results show that the distribution pattern of these sites in the Han, Three Kingdoms, and the Jin Dynasties was spatial dispersion, while in the other periods, it was spatial clustering, and the trend of the nearest neighbor index R was consistent with that of the number of inscriptions. The nearest neighbor index R during the Northern and Southern Dynasties and the Jin Dynasty was relatively close to 1 with the least significant spatial clustering. Meanwhile, during the Qing Dynasty, the index was the smallest with the most significant clustering. Overall, the nearest neighbor index R and critical value Z changed significantly from the Han Dynasty to the New China, reaching 0.128152 and −55.267914 in the Qing Dynasty, respectively, indicating a significant increase in the degree of site clustering during this period (see
Table 2). The main reason for this is that during the Han to the Jin Dynasties, the development of Henan inscriptions had just begun with a relatively small quantity and low correlation. Fortunately, the Central Plains was relatively stable from the Tang Dynasty to the Song Dynasty. With the increase in population and the progress of productivity, the number of inscription sites slightly increased during this period, and the concentration increased as well. However, due to the impact of war in the Jin Dynasty, the number and concentration of these inscriptions decreased. From the Yuan Dynasty to the Qing Dynasty, the Central Plains remained stable. With the further development of productivity, the study of inscriptions gradually matured. During this period, the number of these sites increased significantly, and the degree of site clustering increased, which was the most obvious. During the Republic of China and New China, the inscriptions lost their functional value, and the number and spatial concentration decreased because of modern technology.
3.2. Distribution Direction of Henan Inscription Sites in Different Periods
By analyzing the standard deviation ellipses of the distribution of Henan inscription sites in different periods (
Table 3 and
Figure 5), the overall direction is “south (west) to north (east)”, and the main axis of the ellipses moves toward the northeast. During the Han, Three Kingdoms, and Jin Dynasties, it mainly covered the southwestern and central regions of Henan. During the period from the Northern and Southern Dynasties to the Song Dynasty, it covered the northern and northwestern regions. During this period, the azimuth angle gradually increased, and the distribution trend in the southwest–northeast direction gradually weakened, reaching its weakest point by the Song Dynasty. From the Jin Dynasty to the Ming Dynasty, it mainly covered most of the northern and central regions, with a significant increase in coverage, and the distribution trend was strengthened. The standard deviation ellipse of the Qing Dynasty basically covered the entire area of Henan, with a large number of inscription sites distributed in its various cities. During this period, the azimuth angle was close to 90°, and the distribution trend basically disappeared. From the Republic of China to the New China, it mainly covered the northern and central regions, with a gradually decreasing azimuth angle and a strengthening distribution direction.
The distribution of inscription sites in the above historical periods corresponds to the characteristics of the migration of the center of these sites in different historical periods. The scattered distribution of the inscription sites in different periods mainly focuses on the central (northwest) region of Henan. During the Han Dynasty to the Southern and Northern Dynasties, the center shifted significantly toward the northeast by 155.55 km and reached Jiaozuo. From the Southern and Northern Dynasties to the Sui and Tang Dynasties, the center shifted 66.44 km to the southwest and reached Luoyang. During the Sui, Tang, Five Dynasties, and the Song dynasty, the center shifted 46.98 km northeast and reached Zhengzhou. From the Song Dynasty to the Republic of China, the center slightly moved within Zhengzhou. During the New China era, the center shifted 62.08 km to the northwest and reached Xinxiang. All of these show that the center shifted toward the northeast on the whole, and its speed gradually slowed down.
3.3. Nuclear Density of Henan Inscription Sites in Different Periods
The study of the spatial distribution of inscription sites in Henan during different historical periods is helpful to deepen our understanding and recognition of the relationship between humans and nature, environmental changes, and cultural evolution in Henan [
29].
The number of inscription sites during the Han Dynasty, Three Kingdoms, and the Jin Dynasties only accounted for 0.52% of the total, showing a dotted distribution pattern. They mainly concentrated in Luohe and Nanyang, indicating that the central and southwestern regions of Henan were the center of inscriptions during this period (
Figure 6).
The number of these sites during the Northern and Southern Dynasties accounted for about 2.04% of the total, showing a clustered distribution. They mainly concentrated in Xinxiang and Zhengzhou, and then they spreading toward the northeast and southwest with Xinxiang as the center. Compared with the Han Dynasty, Three Kingdoms, and the Jin Dynasties, the high concentration areas during the Northern and Southern Dynasties migrated northward, and the northern region of Henan became the center of inscriptions during this period (
Figure 6). It was in this period that the number of the sites increased, indicating that their development was relatively good [
30].
The number of Tang Dynasty inscription sites accounted for about 3.28% of the total, and a trend of strip distribution has begun to emerge. There are multiple clusters, which are mainly concentrated in three cities, including Zhengzhou. The most significant one is the high-density cluster located in the west of Zhengzhou. The high-density area has migrated from northern to central and western Henan, indicating that the central and western regions became the center of inscriptions during this period (
Figure 6). The number of Tang Dynasty inscriptions further increased compared to those of the Northern and Southern Dynasties, maintaining a growing trend.
During the Five Dynasties, Ten Kingdoms, and the Song Dynasties, the number of inscription sites accounted for about 3.02% of the total. The overall trend of strip distribution was weakening, and the high-density clusters located in the western part of Zhengzhou continued to gather. At the same time, a high-density cluster located in Jiyuan was formed. In terms of space, the high-density areas of these sites stopped migrating to the west and began to develop toward the northern part of Henan, indicating that the northwest and central regions became the center of inscriptions (
Figure 7). During this period, there was a slight decrease in the number of sites, showing a decreasing trend.
The number of sites in the Jin Dynasty accounted for about 1.25% of the total, with a disappearing trend of strip distribution and a more scattered spatial distribution, returning to the cluster. The high-density clusters located in Jiyuan disappeared, and the same located in the west of Zhengzhou also weakened. However, they still spread from Zhengzhou to the surrounding areas, and the central region of Henan became the center of inscriptions during this period (
Figure 7). The number of these sites showed a significant decrease, further showing a decreasing trend.
The inscription sites during the Yuan Dynasty accounted for about 3.86% of the total number, and their spatial distribution still clustered. However, compared to the Jin Dynasty, they were larger in scale and had a higher degree of clustering. In addition to the high-density cluster located west of Zhengzhou, the cluster located in Jiyuan reclustered and further formed a high-density cluster located in Xinxiang. The central and northern regions of Henan became the center of inscriptions (
Figure 7). The number of these sites increased, showing a growing trend.
The number of the Ming Dynasty inscription sites accounted for about 16.58% of the total, showing a belt spatial distribution. Several high-density clusters further gathered and formed a northeast–southwest belt distribution. The number of sites in the northern region of Henan increased rapidly, which were mainly located in three cities, including Anyang City. The northern region became the center of the Ming Dynasty inscriptions (
Figure 8). The number of these sites continued to increase and maintained a growing trend.
The number of the Qing Dynasty inscription sites accounted for about 58.11% of the total, showing a belt spatial distribution. The high-value areas in the north further gathered on the basis of the Ming Dynasty, and the nuclear density value greatly increased. In addition to the high-value areas in the north, another high-value area was formed in three cities, including Jiaozuo in the northwest of Henan, and showed a scattered trend toward the surrounding areas. The spatial characteristics of northeast–southwest belt clustering in the north and northwest of Henan were basically formed, and the northern and northwestern regions of Henan became the center of inscriptions (
Figure 8). The number of these sites significantly increased, accounting for more than half of the total.
The number of inscription sites during the Republic of China accounted for about 8.71% of the total, still showing a trend of belt spatial distribution. However, compared to the Qing Dynasty, the distribution area of the sites was more concentrated and contracted, mainly concentrating in the northeast, central, and southwest regions of Henan. High-value areas migrated from the north and northwest to the northeast, indicating that the northeast region became the center of inscriptions (
Figure 8). The number of these sites decreased significantly compared to the Qing Dynasty but still exceeded the number of those in other periods except the Ming and Qing Dynasties.
The number of inscription sites during the New China period accounted for about 2.39% of the total with a clustered spatial distribution. The distribution area further contracted compared to the Republic of China and was mainly concentrated in the northern region. Except for the higher density in the northern region, the density in other regions was lower. The northern region of Henan became the center of inscriptions (
Figure 9). The number of these sites in the New China period further decreased compared to the Republic of China. This is mainly due to the decrease in the theme and form of Henan inscriptions after the founding of New China. Most of the inscriptions built during this period were monuments to martyrs, and modern methods were used to record major historical events. Inscriptions only played a commemorative role, resulting in a further decrease in the number of Henan inscriptions during this period.
3.4. Analysis of the Theme and Content of Henan Inscription Sites
Inscription is a common cultural carrier in ancient China and an important way of recording. It not only has diverse forms but also carries a large amount of social information, making it an important part of traditional Chinese culture. It has played an important role in the recording and dissemination of Chinese culture. In terms of the purpose of dissemination and the content of the text, inscriptions can be divided into various types, such as marking, achievement, chronicle, sacrifice and notice [
31]. The 1929 inscription sites in Henan can be divided into five primary themes in terms of content, and they can be further subdivided into 16 secondary themes (see
Table 4). The five primary themes include recording historical events (chronicle tablets), recording historical figures (achievement tablets), religious art (cultural and artistic tablets), boundary tablets (marking tablets), and others (unidentifiable or wordless tablets). Among them, the highest number of inscriptions recording historical events is 1216, accounting for more than 60% of the total, indicating that the main type is chronicle tablets. The recording of historical events can be divided into seven secondary themes: recording the renovation and creation of buildings, major events during the Anti-Japanese War, warning policies, customs and prohibitions, major family events, hydrology and water control of the Yellow River, and major historical events. Among them, the number of events such as the renovation of buildings is up to 592, accounting for more than half of the total number of this category, and it is the main content of chronicle tablets. The recording of historical figures can be divided into five secondary themes: those who praised loyalty and filial piety, those who praised virtue and achievements, the hometown of famous people, those who made contributions during the Anti-Japanese War, and tombstones. Among them, there are up to 110 praising virtue and achievements, accounting for about one third of the total number. It is an important component of achievement tablets. Religion and art can be divided into two secondary themes: statue and portrait, and religious themes. Among them, religious themes have a maximum number of 211, accounting for more than two thirds of the total number of this category. They are the main components of Henan cultural and artistic inscriptions. There is only one secondary theme for boundary tablets, which is the main content of Henan marking tablets. Only 13 of them account for 0.67% of the total number of Henan inscriptions. This is mainly due to the functional nature of boundary tablets, but their position in the theme of Henan inscriptions cannot be ignored.
From a temporal perspective, the themes of Henan inscriptions are mainly chronicle tablets during the Han Dynasty, Three Kingdoms, Jin Dynasties, Yuan Dynasty, Ming Dynasty, and Qing Dynasty. In the Republic of China and New China periods, they are mainly achievement tablets. In the Northern and Southern Dynasties, Tang Dynasty, Five Dynasties, Ten Kingdoms, Song Dynasty, and Jin Dynasty, they are mainly cultural and artistic tablets (see
Table 5). The content of the Henan inscriptions during the Han, Three Kingdoms, and Jin Dynasties mainly consist of two categories: recording major historical events and recording and praising people who have merits and achievements. During the Five Dynasties, Ten Kingdoms, Song Dynasty, Jin Dynasty, and Yuan Dynasty, Henan inscriptions are still mainly based on religion. In the Ming and Qing Dynasties, they were mainly related to the renovation and creation of buildings. In the period of the Republic of China and New China, they focus on those who contributed to the Anti-Japanese War (see
Table 6).
From the perspective of spatial distribution (
Figure 10), the inscriptions on the recreation of buildings are distributed in various cities in Henan with more in the north and less in the south. They are mainly distributed in the northern and western regions of Henan, coinciding with the geographical location of the southern section of the Taihang Mountains. The core areas are located in two cities, including Anyang. The spatial distribution characteristics of creating buildings are similar to those of renovating inscriptions. They are still distributed in the northern and western regions of Henan with the core area located in the northeast–southwest distribution zone of five cities, including Hebi and Luoyang. This is mainly because these areas, as the central cities of Henan Province, are often the development centers of an era with high social prosperity and productivity, featuring frequent building and construction. At the same time, they are more susceptible to war and turmoil, and architectural landmarks are more prone to damage. Therefore, these areas are much more compared to other regions. The distribution of inscriptions on major family events is relatively scattered—mainly in the northern, eastern, and southern regions of Henan. The main core area is located in four cities, including Hebi and Xinyang. Meanwhile, the secondary core area is located in two cities, including Kaifeng. This is mainly because Henan has been the political, economic, and cultural center of China for three thousand years, and there are large families with a long history and lush branches. Inscriptions on the Yellow River hydrology and water control are relatively concentrated, being mainly distributed in its northern part with a small amount in Nanyang. The core area is located in Jiaozuo, which is mainly due to the geographical overlap of these areas with the southern section of the Yellow River. Inscriptions on warning police, village regulations, and customs prohibitions are relatively concentrated, mainly in the central and western regions of Henan, with the core area located in Zhengzhou. This is mainly because in order to face the threat of chaos from the grassroots society, the government has strengthened the grassroots governance and vigorously promoted the village rules and folk conventions. Zhengzhou is located in the center of Henan and is an important area for practicing village regulations and agreements. Inscriptions on major historical events are widely distributed in all cities of Henan, mainly in its north, central and south. The core area is located at the junction of three cities, including Jiaozuo. Due to its long history, major events occurred all over the country, so it is widely distributed. Inscriptions on major events during the Anti-Japanese War are concentrated mainly in the northern and central areas. The core area is located at the junction of three cities including Hebi, where major battles occurred during this period. Inscriptions with themes such as famous people’s hometowns are widely distributed in all cities. The main core area is located at the junction of three cities, including Jiaozuo, as well as the junction of Xinxiang and Hebi. Meanwhile, the sub-core distribution area is located in Nanyang. Inscriptions on tombstones are concentrated, mainly in central Henan, and the core area is located in Luohe and the west of Luoyang. Inscriptions with themes that made contributions during the Anti-Japanese War are relatively concentrated mainly in the northern and central regions. The main core area is located at the junction of three cities, including Anyang, while the sub-core area is located at the junction of three cities, including Jiaozuo. This is mainly because these areas fought major battles during the Anti-Japanese War, commemorating the martyrs and heroic deeds sacrificed here. The distribution on praising meritorious deeds and achievements is relatively wide, with the main core area located in Nanyang and the sub-core area located at the junction of two cities, including Hebi. Inscriptions on praising loyalty and filial piety are scattered mainly in the southern and northern regions of Henan. The main core area is located in Xinyang, and the sub-core area is located in the junction of two cities including Heb, as well as Zhengzhou and Jiaozuo. This is mainly because all the people in Henan will spontaneously or intentionally praise those who have made contributions to the people and have good qualities such as loyalty and filial piety [
32] so as to guide the correct folk customs [
33]. The distribution of statue and portrait inscriptions is relatively concentrated mainly in its central and northern regions. The main core area is located at the junction of three cities, including Jiaozuo, and the sub-core area is located at the junction of two cities, including Xinxiang. These are mainly the inscriptions suitable for depicting this type of theme in these areas with Longmen Grottoes being the example. The distribution of religious themes is concentrated mainly in the central and northern parts; the core area is located in Zhengzhou, which is mainly represented by many famous temples in these areas. The distribution of boundary tablets is scattered, mainly in the north, south and southwest regions of Henan and the junction with other provinces. Its core area is located in three cities, including Jiaozuo, which is mainly determined by the functional nature of these tablets, which are used in the junction of various regions as markers.