Leviticus 17:5
To the end that the children of Israel may bring their sacrifices, which they offer in the open field, even that they may bring them unto the LORD, unto the door of the tabernacle of the congregation, unto the priest, and offer them for peace offerings unto the LORD.
The law required Israel to take the animals they were inclined to slaughter and sacrifice out in the open country and bring them instead to the entrance of the meeting tent. There they were to present them to the priest and offer them to the Lord as fellowship offerings. No sacrifice was to be made at any other place apart from that appointed center. For that reason an altar built east of the Jordan could not rightly stand as another legitimate site for sacrifice or worship.