Albert Barnes Commentary Deuteronomy 12:6

"and thither ye shall bring your burnt-offerings, and your sacrifices, and your tithes, and the heave-offering of your hand, and your vows, and your freewill-offerings, and the firstlings of your herd and of your flock:" — Deuteronomy 12:6 (ASV)

Some have objected that this command could not possibly have ever been carried out, at least not until later days when the territory subject to it was narrowed to the little kingdom of Judah.

But in these and other precepts, Moses no doubt takes much for granted. He is here, as elsewhere, regulating and defining more precisely institutions that had long been in existence. Regarding many details of these institutions, custom made specific legal enactment unnecessary.

No doubt the people well understood what Maimonides expressly tells us concerning this matter: namely, that when immediate payment could not be made, the debt to God was to be reserved until the next great Feast and then duly discharged.

The crucial point to observe was that no kind of sacrifice was to be offered except at the sacred place designated by God for its acceptance.