Land ownership has historically been hereditary and Richard Horsely writes in his book, Covenant Economics, that it was an "inalienable right" for a person to live on and work his father's land. He also indicates that the land actually belonged to the community, that the family were just tenants and caretakers of the land. They lived in houses on the land and it was common practice for a new groom to build an annex to the family home in preparation for his marriage.
The Ottoman Land Code of 1858 required all lands in the Ottoman Empire to be registered. The hereditary tenure system was partially abolished. Some tenants were unaware of this new law. Other tenants refused to register the land, whether because it would obligate them to military services or because they didn't want to or couldn't pay the taxes and fees associated with registration.
Some tenants did end up registering their hereditary land. Others delegated a representative for the community, of which some faithfully registered the land to the various members of the community and others registered the land in their own name. Finally, a few particularly unscrupulous people registered lands they had no rights to and became absentee landlords. Whether all the land was registered or not is unclear based on the sources immediately available to me.
In 1873, the Ottoman Empire passed another land reform that clearly allowed Jews to own land in Palestine. The Zionist movement reacted to this by buying land throughout Palestine. The Zionists were purchasing deeds to these lands, but they weren't necessarily buying them from the tenants. By 1948, Jews owned deeds claiming about 7% of the land in Palestine.
When the Mandate of Israel was formed, the British Empire recognized the deeds issued by the Ottoman Empire. The Jews continued to purchase land in Israel. When the State of Israel formed, many Arabs fled and Israel passed the Absentees' Property Law, reallocating the land that was abandoned. According to this Wikipedia article, some 70% of the land in Israel could have been doubly claimed by a deed from the Mandate of Israel and a deed granted by the Absentees' Property Law.