Abdullah ibn Aamir led the invasion of Khurasan in 650 AD, and his general Rabi b. Ziyad Al Harithi attacked Sistan and took Zaranj and surrounding areas in 651 AD while Ahnaf ibn Qais conquered the Hepthalites of Herat in 652 AD and advanced up to Balkh by 653 AD. Arab conquests now bordered the Kingdoms of Kapisa, Zabul and Sindh in modern-day Afghanistan and Pakistan. The Arabs levied annual tributes on the newly captured areas, and leaving 4,000 men garrisons at Merv and Zaranj retired to Iraq instead of pushing on against the frontier of India. Caliph Uthman b. Affan sanctioned an attack against Makran in 652 AD, and sent a recon mission to Sindh in 653 AD. The mission described Makran as inhospitable, and Caliph Uthman, probably assuming the country beyond was much worse, forbade any further incursions into India.