This chapter examines the differences between Zhe in Northwestern Chinese dialects and the corresponding grammatical forms in non-Han languages in Northwest China. These differences demonstrate that when a grammatical form in Chinese undergoes grammatical change through language contact, this form will not neatly replicate all the usages of the corresponding forms in another language. It is evident that when a grammatical form undergoes grammatical change due to language contact, the process is subject to certain constraints, and these constraints exhibit a certain regularity. Thus, understanding which grammatical rules or principles constrain contact-induced changes is a topic worthy of investigation.