Simplify the following text for a Grade 12 native English-speaking person.
Original: Armenia remained under Ottoman rule for three centuries , until after the Russoâ `` Turkish War ( 1828 â `` 1829 ) , when Eastern Armenia was ceded to the Russian Empire .
Simplified: This condition ended after 300 years when following the Russoâ `` Turkish War ( 1828 â `` 1829 ) , Eastern Armenia was ceded to the Russian Empire .