Complex sentence: The Armenian Oblast (;) was an oblast (province) of the Russian Empire from 1828 to 1840, roughly corresponding to most of present-day central Armenia, the Iğdır Province of Turkey, and Azerbaijan's Nakhichevan exclave.
Split into simpler sentences: The Armenian Oblast (;) was an oblast (province) of the Russian Empire that existed from 1828 to 1840. It roughly corresponding to most of present-day central Armenia, the Iğdır Province of present-day Turkey, and Azerbaijan's Nakhichevan exclave.