The difficulty of logistics and the malarial climate in the south made Han migration and eventual sinicization of the region a slow process. Describing the contrast in immunity towards malaria between the indigenous Yue and the Chinese immigrants, Robert B. Marks (2017:145-146) writes: Over the same period, the Han dynasty incorporated many other border peoples such as the Dian and assimilated them. Under the direct rule and greater efforts at sinification by the victorious Han, the territories of the Lac states were annexed and ruled directly, along with other former Yue territories to the north as provinces of the Han empire.