What did some famous families bring into Hexi Corridor during the Northern and Southern Dynasties?

Buddhism. Dunhuang murals are enough to prove it.

During the Wei, Jin, Southern and Northern Dynasties, the Central Plains was in chaos, and many famous families and literati came to Hexi to avoid the war, which promoted the main road of communication between China and the West. The culture of Hexi Corridor has been promoted as never before. The Liang dynasty established one after another also concentrated a large number of talents. The arrival of aristocratic families in the Central Plains, the improvement of local cultural level and the existence of a large number of scholars provide a knowledge base for the region to accept foreign cultures, and also make it possible for foreign cultures to be transported to the Central Plains. During the late Han Dynasty and Wei and Jin Dynasties, with the arrival of the gentry in the Central Plains, Buddhism soon spread in Dunhuang. The regime change and war at that time provided conditions for the spread and development of Buddhism in Dunhuang.