Móng Cái ( listen) is a city of Quang Ninh province in northern Vietnam, on the border with Dongxing city of China's Guangxi Autonomous Region. It has a population of about 103,000. It is known as one of the wealthiest cities in Vietnam with the average income in some areas exceeding 20,000 USD per family. One of these areas is the Tran Phu ward.