Simplify the following text for a Grade 10 native English-speaking person.
Original: Along with Lake Sevan in today 's Armenia and Lake Urmia in today 's Iran , Van was one of the three great lakes of the Armenian Kingdom , referred to as the seas of Armenia ( in ancient Assyrian sources : `` tÃ cents mtu Å a mÃ cents t Nairi '' ( Upper Sea of Nairi ) , the Lower Sea being Lake Urmia ) . Over time , the lake was known by various Armenian names , including .
Simplified: Along with Lake Sevan in today 's Armenia and Lake Urmia in today 's Iran , Van was one of the three great lakes of the Armenian Kingdom , referred to as the seas of Armenia