Complex sentence: While Vladimir enjoyed hegemony for a time, it too would disintegrate into a series of petty states, the most important of which became Grand Duchy of Moscow, which itself would eventually evolve into the Tsardom of Russia.
Split into simpler sentences: While Vladimir enjoyed hegemony for a time, it too disintegrated into a series of petty states. The most important of these became Grand Duchy of Moscow, which itself eventually evolved into the Tsardom of Russia.