**1. Introduction**

Settlements are a concrete manifestation of human occupation of the earth's surface and are an important part of the formation of the surface's form. At the same time, ancient settlements are places where ancient humans lived and carried out their production and social activities; they contain the rich material and spiritual connotations of human developmental history and are a valuable cultural heritage and spiritual treasure for contemporary times. Their temporal and spatial distribution was influenced by environmental, cultural, and political factors with different characteristics. The past, present, and future are in the same chain of time. The study of the spatial and temporal distribution and morphological characteristics of settlements can, therefore, provide a basis for the conservation of their heritage value, as well as be a reference for the reconciliation of human–land relations, thus contributing to global sustainable development.

The spatial distribution of settlements has been a subject of interest for a long time in a number of disciplines, including archaeology, geography, and architecture. Geographic Information Systems (GIS) have been applied to archaeological research since the 1980s. With the further development of GIS technology, there have been many successful examples

**Citation:** Tong, M.; Li, B.; Li, Z. Research on the Spatial–Temporal Distribution and Morphological Characteristics of Ancient Settlements in the Luzhong Region of China. *Land* **2022**, *11*, 1579. https:// doi.org/10.3390/land11091579

Academic Editors: Lucia Della Spina, Paola Pellegrini, Antonia Russo, Maria Rosa Valluzzi and Angela Viglianisi

Received: 11 August 2022 Accepted: 13 September 2022 Published: 15 September 2022

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**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

of the application of GIS to settlement archaeological research, and the theory is gradually becoming mature [1]. In recent years, numerous scholars have carried out studies on the Yangtze River basin [2], the Minjiang River basin [3], the Dalian region [4], the Ili River valley [5], and other regions within China. However, relatively few similar studies have been carried out in the lower reaches of the Yellow River Basin. Shandong, located on the lower reaches of the Yellow River, is one of the important birthplaces of Chinese civilisation, and archaeological work has shown that its cultural genealogy is well established. In chronological order, it includes: Yiyuan Man (about 400 ka B.P.), Xintai Wuzhutai Homo Sapiens (about 50–20 ka B.P.), the fine stone tool remains of the Yishu and Wensi river basins (about 10 ka B.P.), the early Neolithic culture (about 8.4–7.7 ka B.P.), the Beixin culture (7.3–6.1 ka B.P.), the Dawenkou culture (6.1–4.6 ka B.P.), the Longshan culture (4.6–4.0 ka B.P.), the Yueshi culture (4.0–3.6 ka B.P.), and all subsequent historical periods. Each of these periods are closely linked, and the cultural traditions have evolved in the same way [6]. Within Shandong province, the Luzhong region (the centre of Shandong Province) is a relatively independent climatic, geographical, and cultural unit. Moreover, the political, economic, and cultural centre of Shandong has been located within this area since Linzi of Qi in the Spring and Autumn period. The Luzhong region is, therefore, a valuable case for studying the spatial and temporal distribution and characteristics of settlements at the core of Chinese civilisation. It can also enrich the case of settlement studies in the lower Yellow River Basin.

#### **2. Materials and Methods**

The spatial extent of this study, the Luzhong region, specifically includes Jinan (except Jiyang District and Shanghe County), Zibo (except Huantai County and Gaoqing County), Tai'an, and Weifang (Figure 1). The climate in the Luzhong region is temperate monsoonal, with a more pronounced continental character. It is cold and dry in winter, and hot and rainy in summer. The average annual temperature is 12 ◦C–14 ◦C, and the annual precipitation is approximately 680–860 m [7]. As can be seen from the map, the region has the Taiyi Mountains in the centre, which are surrounded by hilly undulations that transition into flat plains. In terms of water systems, the Yellow River flows through the territory. In addition, there are dense small- and medium-sized rivers, which have also developed their own water systems. This study covers the period from the Neolithic period to the Qing dynasty and is divided into six time periods according to cultural sequences: Neolithic, Shang and Zhou, Qin to Northern and Southern Dynasties, Sui to Five Dynasties, Song and Yuan, and Ming and Qing.

Based on the temporal and spatial scope of the study, a total of 1972 settlements were selected from the State Administration of Cultural Heritage [8] and the National Cultural Heritage Administration [9] by using "ancient city", "old city", "settlement site", "fortified cities", "fortresses", "castle", and "mountain city" as keywords. These data include all levels of cultural relic protection units and historic cities, towns, and villages. Thus, the data selected balanced representativeness and breadth, and they are able to reflect the spatial and temporal distribution characteristics and evolution patterns of settlements in the central Shandong region. In addition, the Digital Elevation Model (DEM) of the Luzhong region required for the research was derived from the GDEMV3 30 M resolution digital elevation data from the Geospatial Data Cloud website.

This paper analyses the spatial–temporal distribution and morphological characteristics of ancient settlements in the central Shandong region based on data from 1972 settlements and with the aid of a GIS system. Specifically, first, the 1972 data collected were divided into 6 stages according to cultural sequences (Neolithic, Shang and Zhou periods, Qin to North and South Dynasties, Sui to Five Dynasties, Song and Yuan Dynasties, Ming and Qing Dynasties) to establish a database of settlement attributes and perform kernel density calculations. Then, in the QGIS 3.22 software environment, the DEM map of the Luzhong area was overlaid with the settlement points to carry out the calculation of the elevation, slope, aspect, and buffer zone. At the same time, the spatial and temporal

distribution characteristics of the settlements are comprehensively explored in relation to the historical context and dominant cultural forms in which the settlements were located. Based on the above quantitative and qualitative analyses, the distribution and evolutionary characteristics of the settlements are derived.

**Figure 1.** Location and scope of the Luzhong region.
