Original: Along with Lake Van and Lake Urmia, Sevan was one of the three great lakes of the historical Armenian Kingdom, collectively referred to as the Seas of Armenia; it is the only one within the boundaries of today's Republic of Armenia.
Simplified: Sevan was one of the three great lakes of the historical Armenian Kingdom, collectively referred to as the Seas of Armenia, and it is the only one within the boundaries of today's Republic of Armenia.