“When the Israelites heard this, the whole community of the Israelites assembled at Shilo to make war on them” JOSHUA 22:12 (The Israel Bible™)
When the 2½ tribes residing on the east bank of the Yarden set up an altar to Hashem, the other tribes react harshly and quickly. The 9½ other tribes threaten to make war if they do not put an end to this practice. Because the Mishkan stands, no other altars could be permitted. Similarly, once the Beit Hamikdash is built in Yerushalayim, no sacrifices are ever allowed anywhere else. Though the entire Land of Israel is holy, Hashem desires that His people join together to serve Him in one united center of worship, in the heart of the capital city Yerushalayim.