The age of the earliest layers of Bukhara urban culture is 2500 years. Legends say that the most ancient monuments are the well of Job - Chashma-Ayub and Ark citadel at the gate of which there was a tomb of cultic hero Siyavush. According to a version 'BUKHARA' goes from Sogdian word 'BUXARAK' - 'happy place'. Local governors have had their own coins since the 2nd century B.C. In the 7th century Bukhara united princedoms had governors with a title of Bukhar-hudat. Historian Narshahi informed that Bukhar-hudat Bidun reconstructed Ark according to constellation of Ursa Major. In the early 8th century Arabian commander Quteiba conquered Bukhara and constructed the first mosque of Banu Hanza-la. At the end of the 9th century Central Asian Interfluve went out of the Arab power. There was formed the state of Samanids with its capital in Bukhara. The city grew much during 9th-10th centuries. Not only the city (shahristan) but also its trade and craft suburbs (rabad) were walled. The walls protected the city till the 20th century Remains of the wall and medieval gate are still available.