The country of Israel is an interesting case study in land ownership. At the beginning of the 20th century, as I understand it, the region was known as Palestine and it was occupied by Palestinians, under Turkish rule. By the end of the century, the region was known as Israel and a large chunk of it was mostly occupied by Jews. How did this come about, and what were the rights and wrongs of the matter?
It seems to me that none of the arguments of either side is 100% satisfactory, but I'll list some of the better arguments first and deal with the rest later.
As I've discussed elsewhere, it seems to me that no-one has a strong moral claim to own land.
Probably in no country in the world does buying land from private owners give you a right even to live there: the government can throw you out at its own discretion. As for setting up your own government on the land you've bought: forget it.
The Jews who came to Palestine found it in a period of exceptional vulnerability, with no government interested in defending Palestinian interests; and they took full advantage of that vulnerability to take over the country for themselves — attempting to drive out the Palestinians as the European settlers in North America drove out the American Indians.
In earlier centuries, that kind of behaviour was normal and common. By the mid-twentieth century, I think we can call it unscrupulous and unattractive.
The long-running slow war in Palestine is discreditable to both sides, who are both killing innocent civilians with remarkable unscrupulousness. The fact that one side does it doesn't entitle the other side to do it (two wrongs don't make a right). Furthermore, it's quite obvious that neither side is achieving anything by all this violence. They do it only to satisfy their desire for revenge. Both sides should stop kidding themselves that they're achieving anything, and should stop the killing immediately and unconditionally — in their own interests.
Also discreditable was the behaviour of successive British governments who caused this whole problem by permitting the Jews to take over Palestine against the strong opposition of its inhabitants. More recently, the American government has repeatedly tried to make peace in the region, but has been too pro-Israeli to be taken seriously as an umpire.
Of course, by now Israel is an established fact, and any Israeli who was born there is by definition a native of the region, who I reckon has the same moral right to live there as any other native. As there are also plenty of Palestinian natives, this leaves the region in an unhappy mess.
The Palestinians could equally well claim that their God gave it to them. As I don't believe in gods, this argument means nothing to me.
The ancient Israelis lived there thousands of years ago. If everyone had the right to claim land because their ancestors lived there thousands of years ago, there would be chaos worldwide. Therefore, if there were any effective international law, such a right would never be included in it.
No-one's objecting to Jews having a country of their own. But they weren't morally entitled to take another people's country without their consent. And that consent was plainly lacking.