Bahram Vallis is an ancient river valley in the Lunae Palus quadrangle of Mars at 20.7° north latitude and 57.5° west longitude. It is basically a single trunk valley, with scalloped walls in some places. The presence of streamlined erosional features on its floor shows that fluid was involved with its formation. (wikipedia entry)
A vallis is a valley. On Mars large valles are named after words for Mars/star in various languages. Small valles are named after classical or modern names of rivers.