Complex sentence: But the Chinese kept a heavy military lineup in Yunnan, and threatened another invasion for another decade, forcing him to refrain from renewing the war with Siam even as the Siamese consolidated their gains.
Split into simpler sentences: But the Chinese kept a heavy military lineup in Yunnan, threatening another invasion for another decade. He was forced to refrain from renewing the war with Siam even as the Siamese consolidated their gains.