[A]rchaeologists have found a total of some 900 rock carvings, or "petroglyphs," at Al Jassasiya. They are mostly enigmatic cup marks arranged in various patterns, including rows and rosettes, but also eye-catching representations of sailing ships, usually seen from above but also depicted in linear profile, among other symbols and signs. Of all the documented single figures and compositions, more than a third consist of cup marks in various configurations, shapes and sizes. The most prominent pattern involves two parallel rows of seven holes, leading some to believe that these were used to play mancala, a board game popular in...