Complex sentence: Lê Thái Tông became increasingly unhappy with his regent's actions and sought out support from the rivals of Le Sat. He made an alliance with Trinh Kha (who had been sent to a distant part of Vietnam).
Split into simpler sentences: Lê Thái Tông became increasingly unhappy with his regent's actions and sought support from rival factions. He struck an alliance with Trinh Kha (who had been sent to a distant part of Vietnam).