Adam Clarke on Joshua 22:1

Then Joshua called the Reubenites, etc. - We have already seen that 40,000 men of the tribes of Reuben and Gad, and the half tribe of Manasseh, had passed over Jordan armed, with their brethren, according to their stipulation with Moses. The war being now concluded, Joshua assembles these warriors, and with commendations for their services and fidelity, he dismisses them, having first given them the most pious and suitable advices. They had now been about seven years absent from their respective families; and though there was only the river Jordan between the camp at Gilgal and their own inheritance, yet it does not appear that they had during that time ever revisited their own home, which they might have done any time in the year, the harvest excepted, as at all other times that river was easily fordable.