The Achaemenid Empire expanded as far as the Oxus today's Amu Daryai River in Uzbekistan, Tajikistan, Turkmenistan and Afghanistan, in and the Jaxartes today's Syr Darya River in Kyrgyzstan, Uzbekistan, Tajikistan, and Kazakhstan to the north and north-east.
The Protectorate General to Pacify the West, or Anxi Protectorate (640 CE–790 CE) was a protectorate established by the Tang Dynasty in 640 to control the Tarim Basin. The head office was first established at the prefecture of Xi, now known as Turpan, but was later shifted to Qiuci (Kucha) The Four Garrisons of Anxi in Kucha, Khotan, Kashgar, and Karashahr were installed between 648 and 658 as garrisons under the western protectorate. In 659 Sogh (Chuy Region), Ferghana, Tashkent, Bukhara, Samarkand, Balkh, Herat, Kashmir, the Pamirs, Tokharistan, and Kabul all submitted to the protectorate under Emperor Gaozong of Tang.
Silk Road Research 