The name Θῖναι, Strabo, Σῖναι, Ptol., Τζίνιτζα, Kosmas, did not obtain currency first from the founder of the dynasty Tsin; but, long before this, Tsin was the name of a feudal kingdom in Shensi, one of the western provinces of the Sinese land, and Feitsa, the first feudal King of Tsin, began to reign as early as b.c. 897.
Source: wiktionary