Complex sentence: The khanate was under suzerainty of Persian Empire, a dependency of much stronger Quba Khanate for most part of 18th century conquered by Alexander I of Russia and was incorporated into Russian Empire in 1806.
Split into simpler sentences: The khanate was under suzerainty of Persian Empire, a dependency of Quba Khanate for the most part of the 18th century. Conquered by Alexander I of Russia and was incorporated into Russian Empire in 1806.