Does the bible end (for you) after Jesus was crucified???
The sheep being spoken of are the "Lost sheep of the House of Israel". [Matthew 10:5-6] Our Saviour tells the Twelve not to visit the Gentiles....but go to the House of Israel.
During the first century the area around Jerusalem was known as Judea. Earlier in history it had been known as Judah [II Kings 17:18-23]. The Lost sheep were called "Israel....the Northern Kingdom" and the Southern Kingdom was called Judah.....and Judah was never lost! The Nation of Judah also included the tribe of Benjamin and a portion of the priestly tribe of Levi [I Kings 12:23][II Chronicles 11:1].
The reason the Northern Kingdom was called lost is because they never returned from their Assyrian captivity [verse 23][II Kings 17:6]. In fact, the Assyrian King brought people from Babylon to inhabit the area the Israelites were taken from [II Kings 17 24]. These people still resided in Samaria during the first century and that is where Simon Magus comes from [Acts 8]. The people of Judah (Jews) did return from their Babylonian captivity later in scripture and you will find the return noted in the Books of Ezra and Nehemiah. You will find three tribes mentioned in these books; Judah, Benjamin and their share of the priestly tribe of Levi. There is no mention of the other ten tribes in these scriptures.....meaning they were lost from scripture. The Lord had decided to remove the Northern ten tribes from history [I Chronicles 17:9-10].
There is great distinction in both the Old and New testaments when it comes to these two "Houses of Israel". Both are mentioned numerous time in prophecy, both separately and jointly....but they are two separate entities and when New Testament scripture refers to the "Lost Sheep" or "Feed my Sheep" or "Take care of my Sheep" or "Feed my Lambs" our Saviour is referring to the Nation of Israel[ Matthew 10:6][Matthew 15:24].
To reiterate....the Twelve and subsequently, the Eleven were instructed to evangelize these "Lost Ten Tribes" and not go to the Gentiles. There were plenty of other disciples for that task [Acts 1:15][Acts 2:40]. That is why we say that Peter's primary task was not in Rome....and it is very doubtful he even went there.