The economy of the province is largely dictated by its capital city, Thái Nguyên, which is the fastest growing city of North Vietnam. The city is the gateway to northwest Vietnam. It is famous for its tree plantations. Its historical importance is due to the fact that Ho Chi Minh resided here in the Phu Dinh village of Dinh Hoa district when he planned "Dien Bien Phu". Before he moved to Hanoi, he came here from Tan Trao and declared independence. The city is also the centre of heavy industries of northern Vietnam. Thái Nguyên Iron and Steel Company (TISCO), which is located in Thái Nguyên city, is one of Vietnam's top 20 state-owned companies, and has made a sizable contribution to Vietnam's economy. The city is located on the bank of the Cầu River has a geographical area of approximately and its population was 228,064 in 2005.