The Yama clan is a clan that originated in the Land of Mountains. They are very powerful Earth Jutsu users. They do not have a Clan Leader instead they have a Clan Council. When Itachi, Sasuke, and Ryun Uchiha created the Village Hidden in the Mountains they moved in and established their base in the village.
Tsuchi Seichuu (literally, Earth Control)
Members of the clan can control and distort the the ground into any shape or form. They can also form weapons from rocks. Genin level clan members can create simple things such as kunai and shruiken. Chunin level clan members can create small hills, spears, and even swords from rock. Jonin level clan members can create medium sized hills and pretty much any weapon.