If the Bible were to only say that Israel would come back after being conquered by the Romans, then ehm it wouldn't be thaaaat much of a prophecy. The Bible said Israel would come back, and also when Israel would come back.
"Then take an iron pan, place it as an iron wall between you and the city and turn your face toward it. It will be under siege, and you shall besiege it. This will be a sign to the house of Israel. "Then lie on your left side and put the sin of the house of Israel upon yourself. You are to bear their sin for the number of days you lie on your side. I have assigned you the same number of days as the years of their sin. So for 390 days you will bear the sin of the house of Israel. "After you have finished this, lie down again, this time on your right side, and bear the sin of the house of Judah. I have assigned you 40 days, a day for each year."
1. Ezekiel said the Jews were to be punished for 430 years because they had turned away from God. As part of the punishment, the Jews lost control of their homeland to Babylon. Many Jews were taken as captives to Babylon.
2. Babylon was later conquered by Cyrus in 539 BC. Cyrus allowed the Jews to leave Babylon and to return to their homeland. But, only a small number returned. The return had taken place sometime around 536 BC, about 70 years after Judah lost independence to Babylon.
3. Because most of the exiles chose to stay in pagan Babylon rather than return to the Holy Land, the remaining 360 years of their punishment was multiplied by 7. The reason is explained in Bible's book of Leviticus. (Leviticus 26:18, 26:21, 26:24 and 26:28). In Leviticus, it says that if the people did not repent while being punished, the punishment would be multiplied by 7. And, by staying in pagan Babylon, most exiles were refusing to repent.
4. So, if you take the remaining 360 years of punishment and multiply by 7, you get 2,520 years. But, those years are based on an ancient 360-day lunar calendar. If those years are adjusted to the modern solar calendar, the result is 2,484 years.
(A better explanation of 4 will come at the bottom of this post)
5. And, there were exactly 2,484 years from 536 BC to 1948, which is the year that Israel regained independence.
(taken from http://www.watchmanbiblestudy.com/Articles/1948PropheciesFulfilled.htm
permission to use automatically granted in notice on bottom of the page)
A better explanation of 4 from (http://www.hebroots.org/hebrootsarchive/9808/9808_m.html):
The Babylonian captivity ended in the spring of 536 B.C.E., 1st Nisan.
This date is the starting point for our calculations.
The period of worldwide captivity would last 2,520 biblical years x 360 days = 907,200 days.
Converting this figure into our calendar year we divide the 907,200 days by 365.25 to reach a total of 2,483.8 calendar years.
(Remember that there is only one yearbetween 1 B.C.E. and 1 C.E.; there was no Year Zero). The end ofIsrael's worldwide captivity would occur after a total of 2,483.8 years had elapsed from the end of the Babylonian Captivity in thespring of 536 B.C.E.
End of Babylonian Captivity: Spring 536 B.C.E. + the duration of Worldwide Captivity: 2,483.8 Calendar Years = When the Worldwide Captivity would end: Spring 1948.
The Rebirth of Israel: May 14th 1948