Abstract Sinitic languages are known for their SVO order and mostly isolating morphology. This study addresses eleven languages of four different areas in Hunan, Yunnan, Sichuan, and Qinghai/Gansu provinces in China that possess SOV order and developed a postnominal flagging system. This study presents a synchronic description as well as a diachronic analysis of the flagging systems in these languages, focusing on typological properties (ergative or secundative alignment) and the role of language contact. The existence of four separate areas with limited mutual contact allows a contrastive approach and inferences on the role of different contact languages (Tibetic, Mongolic, Tujia) or different types of language contact (borrowing of flags, shared grammaticalization). The study argues against OV order and postnominal flagging as defining features of the “Amdo Sprachbund”, showing that these are universally present in all four areas and are better understood as the result of contact between two Eurasian macro areas.