Read Ezra 1-2 at Bible Gateway.
Then the heads of the fathers’ houses of Judah and Benjamin, and the priests and the Levites, with all whose spirits God had moved, arose to go up and build the house of the LORD which is in Jerusalem. Ezr 1:5
The Medians and Persians overthrew the Babylonians after the Babylonian empire had ruled for seventy years.
When the twelve tribes of Israel split into two kingdoms during the reign of Rehoboam the son of Solomon, Benjamin stayed with Judah in the southern kingdom (commonly known in the prophets as the house of Judah) while the other ten tribes became the northern kingdom (commonly known in the prophets as the house of Israel or Ephraim). I think it is awesome and amazing, that when Judah made himself surety for Benjamin to his father Jacob (Gen 43:8-9), that the tribe of Judah remained surety for the tribe of Benjamin throughout their history.
The ten tribes of the northern kingdom were taken captive by the Assyrians in 721 bc and have not yet returned. The two tribes of the southern kingdom, which were taken captive by Nebuchadnezzar in 586 bc, were returning after seventy years under the leadership of Ezra the scribe.
From the time of the Babylonian captivity, the remnant of Judah, Benjamin, and the priests and Levites who returned to Judah and Jerusalem were known as Jews (of Judah). The people among whom Messiah Yeshua was born, were Jews.
I often hear people ask, when they learn that I rest on the Sabbath, “Oh, are you Jewish?” In other words, Are you one of the remnant of two of the tribes, with Levi, who were returned to Judah from the Babylonian captivity? No, I reply. The command to rest on Sabbath was given to the twelve tribes, all the children of Israel, and not just to the two tribes and Levi. Someone does not have to be Jewish to rest on the Sabbath or obey the LORD’s commandments.
Often people ask me why I celebrate the Jewish feast days of Passover or Trumpets, rather than the Christian feast days of Christmas or Easter. Passover, Trumpets, and the rest are not Jewish feasts — applicable only to the two tribes and Levi. They are the feasts of the LORD (Lev 23:2), and the LORD commanded the twelve tribes, all the children of Israel, plus the Gentiles who would join themselves to Israel’s God with them, to keep them.
In fact, Torah is not the provence of Jews only, the two tribes and Levi, but it is the heritage of all the children of Israel, including those of the house of Ephraim, who might to this day find themselves among Gentiles and Christians.
In Ezra, we begin to see the LORD fulfill the promise He made to the house of Judah, to return them to their land. He also made that promise to the house of Ephraim, and although it has not been fulfilled yet, He will fulfill it. He will fulfill it!