Some scholars have wondered why Mary and Joseph, both descendants from the tribe of Judah, were living in Nazareth in northern Israel.
In ancient times after King Solomon died, the kingdom of Israel in the north had split away from the kingdom of Judah in the south. The tribes in Judah (Judea) were the tribes of Judah, Levi, and some of Benjamin. (The Levites served in the Temple.)
King Jeroboam in the north ruled the other tribes and he didn’t want them going down to Jerusalem to make pilgrimages to the temple. He set up two altars for worship in Samaria and way up north in Dan. These centers for worship had the people of Israel worshipping a golden calf, “the god who led them out of Egypt.” This didn’t sit very well with the righteous, especially if they were from the tribes that were in the majority in Judea, so these people tended to move back to the south.
Around 730 B.C. the northern kingdom of Israel was attacked by the Assyrians who were exceptionally ruthless. They killed many and carried others away to Assyria. They transplanted loyal subjects from around the empire into Israel.
Around 600 B.C. the Babylonians attacked Judah. The Babylonians were ruthless, too. They killed many and carried others away to Babylon, leaving behind only those who were very poor, lower-class people. Instead of a thriving city, Jerusalem was a backwater ruin while the Jews were captive in Babylon. They started to return about 70 years later but it took a long time to rebuild.
Around 330 B.C. the Greek Empire overran both Israel and Judea. In about 175 B.C. a farming family, the “Maccabees,” fought off a Greco-Syrian alliance. The Maccabees took charge of the southern kingdom and they were called the Hasmonean Dynasty simply because Matthias, the father in the family, was from a place called Hasmonea.
The Hasmoneans were in power (and very corrupt) when the Romans came in. They had had some success in expanding Judea’s territory into the north. Some scholars think that anyone up there from the tribe of Judah must have had some sort of government job that reported back to Jerusalem. So perhaps the grandparents and parents of Mary and Joseph had served the Hasmonean government in some way. We do know that Mary and Joseph themselves were very faithful Jews who made pilgrimage with their extended family to Jerusalem for the High Holy Days.