Commendable Caution and Concern

As the warriors of the 2.5 tribes to the east of Jordan are sent home having finished assisting the 9.5 tribes to the west, they set up an altar, causing alarm bells to ring among their brethren and raising the spectre of a civil war. But what is their real motivation? Are their brethren over-reacting? Here we see much to commend and copy on both sides!