Objective The Nanjiang Ancient Road is a uniquely distinctive ancient waterway among the ancient post roads in southern Guangdong. The settlements along its route flourished because of the road. Although the scale and prosperity of individual settlements are not comparable to those in other parts of Lingnan, under the influence of multicultural integration, the value of the multicultural landscape characteristics presented by these settlements is prominent. Exploring the characteristics and influencing factors of settlement landscapes from the macro perspective of "cultural route" can break through the point-like research model of "studying a village in isolation" and help tap the multi-dimensional value of settlements.

Methods The cultural route focuses on integrity and emphasizes the cognition of cultural phenomena through dynamic and historical functions, which provides a holistic research perspective for the study of settlement landscape along the Nanjiang Ancient Road. Therefore, based on the theoretical framework of “human - land - property” of cultural geography, combined with field investigation and GIS spatial analysis, using typology analysis method, from the three functional dimensions of nature, commerce and culture of cultural routes, 65 traditional settlements along the Nanjiang Ancient Road were selected as the research object, and the landscape characteristics and influencing factors of settlements along the ancient road were analyzed.

Results 1) As an important traffic foundation for the formation and development of settlements, the ancient road has a significant impact on the differentiation of landscape types. The settlement landscape of Nanjiang Ancient Road can be divided into three categories: natural landscape, commercial landscape and cultural landscape, with different spatial distribution, morphological characteristics and cultural characteristics. The settlements along the Nanjiang Ancient Road present natural landscape characteristics of “rich layers, mountains and waters embracing each other”, “following the terrain and conforming to the wind and water”, and “digging canals to divert water, preventing floods and building dikes”.2) The commercial function of the Nanjiang Ancient Road and the formation of the commercial landscape of settlements have a mutually promoting relationship, forming commercial landscapes of “land and water transportation facilitating each other, ferries interweaving” and “setting up fairs by the water, forming markets along streets”.3) During the Ming and Qing dynasties, the “policy of recruiting people to settle and be registered” spurred a large number of immigrants to move in along the Nanjiang Ancient Road, establish clans and found villages. The mutual exchange of immigrant cultures gave rise to cultural landscapes featuring “separation of residences and ancestral halls, mixed styles” and “pantheistic worship, creating landscapes by making use of water”. In the Ming and Qing Dynasties, the Ming government encouraged people to migrate here, and the policy of granting household registration prompted a large number of immigrants to move along the Nanjiang Ancient Road, establish clans and set up villages. This led to the formation of diversified and mixed - style landscapes of residences and ancestral halls as well as religious cultural landscapes, boasting unique regional cultural characteristics of Nanjiang.

Conclusion The settlements along the Nanjiang Ancient Road are the spatial carriers of natural landscape, commerce, culture and other functions. The population base provided by the immigration policy is the starting point of its development. Under the background of multicultural integration, the settlements along the Nanjiang Ancient Road form a unique landscape. As a key factor, immigration policy provides the necessary population base for the formation of settlements along the route, and is the starting point of settlement development. The distribution and rise of immigrant settlements along the Nanjiang Ancient Road benefited from the efficient water transportation system constructed by the ancient road water network, and the commercial development of settlements along the route flourished. Population mobility and trade promote each other, which greatly promotes the exchange and integration of immigrant culture. Birth of Nanjiang regional cultural landscape. Revealing the landscape characteristics and influencing factors of settlements along the cultural route from the perspective of integrity and dynamics can provide a basis for the overall protection of settlements along the Nanjiang Ancient Road. Under the rapid urbanization, the protection of settlement landscape along the Nanjiang Ancient Road has encountered severe challenges such as the decline of traditional features and the imbalance of development. In the reconstruction of settlement landscape, we should adhere to the principles of integrity, dynamics and sustainability of cultural route protection, integrate natural and human landscape resources, and rationally activate and utilize settlement landscape. Through the chain of beads, the implementation of zoning-subsection-grading differentiation development, the construction of the overall spatial control system for the protection of the settlement of the Nanjiang Ancient Road, the creation of cultural routes for the integration of ecology, culture and industry, the creation of a settlement memory scene carrying nostalgia, and the promotion of the revitalization and development of settlements.