Complex sentence: Yusuf Khan no longer had the ability to launch an offensive into Puli Thevar's country so he stayed at Tirunelveli and posted his men at key points to limit Puli Thevar's raids.
Split into simpler sentences: Yusuf Khan no longer had the ability to launch an offensive into Puli Thevar's country. So he stayed at Tirunelveli and posted his men at key points to limit Puli Thevar's raids.