I read recently that it is supposed that Jews had already long established communities down every trade route, including via sea, and that rather than any imposed diaspora there was an abandonment of Jews by Jews after the economic infrastructure was destroyed by the Romans arround 70 AD. So the Holy Land was abandoned by the Sanhedren, the poor Jews had to stay, the upper crust left them to their own devices. I will get you the authors name when my rolodex starts working again.
So much for proof of ownership. So then. NO! Israel has no right to exist.
"Rome beats us up and we left for better money and less sand" is no excuse to kick out the inhabitants of a legally formed nation.