The Romans never barred the Jews from Judea, which they had renamed Palestine: they barred the Jews from Jerusalem only. Some Jews have continued to live in Israel/Palestine without interruption, in larger or smaller numbers throughout the recent millenia.
However, the possibility of a large-scale Jewish return to Palestine/Israel never came to fruition until the last 135 years, mainly because of poverty, the dangers of travel, the hostility of the Ottomans and others, and the barrenness of the land.
Poverty: most of the Jews were not well-to-do in their places of exile; but the poverty in Palestine was much worse.
The dangers of travel: crossing the Mediterranean was fraught with more than one kind of danger; loss of ships was not uncommon. But overland travel was even more risky for Jews, whom everyone felt free to pillage.
Barrenness: until the draining of swamps and desert cultivation got underway with modern technology, much of Palestine was too arid or too wet for crops.
The Exile of Jews from palestine is known as the Diaspora
Because Palestine keeps attacking the Jews.
no
No. Jews had already been migrating to Israel/Palestine in substantial numbers since 1919.
There have always been Jews in Palestine. They were not the majority between the years 132 CE and 1949 CE.
The declaration gave the Jews of Palestine the hope that they might one-day have a country of their own.
Jews did not leave Palestine in 65 BCE. They were forcibly exiled over a century later in 70 CE.When they were exiled, they took on an incredible number of occupations. In most European countries, they were banned from a number of those occupations (especially artisanry). This resulted in European Jews primarily becoming lawyers, bankers, and doctors, since these were the professions not barred to them. However, in countries like Yemen where these prohibitions never occurred, Jews were dominant in jewelry creation.
Diaspora.
no
Sanhedrin
they had part of palestine.
The Muslims and Jews both claim that Palestine is their land at that they have been living there for thousands of years. The Muslims do not have any proof of their claim, but the Jews do.