 China opened up camps to train the Afghan Mujahideen near Kashgar and Khotan and supplied them with hundreds of millions of dollars worth of small arms, rockets, mines, and anti-tank weapons.Since the late 1970s Chinese economic reform exacerbated uneven regional development, more Uyghurs have migrated to Xinjiang cities and some Hans have also migrated to Xinjiang for independent economic advancement.Increased ethnic contact and labor competition coincided with Uyghur separatist terrorism from the 1990s, such as the 1997 Ürümqi bus bombings.