Through a case study on the Zijun Samatao community of Kunming City in Yunnan Province of China, this paper discusses the impact of urbanization and mass Han Chinese migration on the endangerment of an ethnic minority language and culture. Samatao of Kunming is a subgroup of the minority Yi nationality of China. Historically, Kunming was the original homeland of many Yi communities including the Samatao. With the fast pace of urbanization and increasing Han Chinese migration, the Samatao community is losing their language and has lost their traditional culture and religion. Urbanization has brought mass migration into Zijun village, accelerating the endangerment of the Samatao language. Of nearly three thousand registered Samatao people, fewer than 100 (including semi-speakers) have any level of active knowledge of their language and culture. Since 1994, the endangerment of Samatao language has dramatically increased, especially since 2003. Based on data from fieldwork in the community over more than twenty years, this paper explores how the ideals of the Samatao community about preserving their language and culture are challenged by the contextual reality of urbanization and mass Han Chinese migration.