When Turkic-speaking Tabghatch conquered and ruled China for nearly 200 years (386-581), they adopted Chinese written language as a tool for governance. The ruling Turkic officials were then engaTurkicged in a large scale second language acquisition (SLA). On the grass-root level, they also adopted Chinese characters to script Turkic language resulting into Xianbei National Language, Turkic scripted in selected Chinese characters. Sharing the same platform, Turkic and Chinese in medieval China has opportunity in code-mixing. Bianwen preserved such code-mixing. Because of prolonged Turkic socio-politico-econmomic dominance, Turkic functional expressions were favored among the bilingual communities and eventually northern vernacular of Chinese language is converted into with strong presence of Turkic functional expressions. The elements discussed in this paper are examples of converted Turkic in Mandarin.