sentences:  Three of the commanderies fell or retreated westward within a few decades, but the Lelang commandery remained as a center of cultural and economic exchange with successive Chinese dynasties for four centuries.At its administrative center in Lelang, the Chinese built what was in essence a Chinese city where the governor, officials, and merchants, and Chinese colonists lived.Their administration had considerable impact on the life of the native population and ultimately the very fabric of Gojoseon society became eroded.