Deuteronomy 12:6

Some have objected that this command cannot possibly have been ever carried out, at all events until in later (lays the territory which owned obedience to it was narrowed to the little kingdom of Judah. But in these and in other precepts Moses doubtless takes much for granted. He is here, as elsewhere, regulating and defining more precisely institutions which had long been in existence, as to many details of which custom superseded the necessity of specific enactment.