Complex sentence: After Pskov became independent, Russa became the second most important town and trade center of the Novgorod republic after Novgorod itself; by the end of the 15th century it contained about 1,000 homesteads.
Split into simpler sentences: After Pskov became independent, Russa became the second most important town and trade center of the Novgorod republic after Novgorod itself. By the end of the 15th century it contained about 1,000 homesteads.