Probably the only way this is possible is if there is a Jewish kingdom which survives the fall of the Roman Empire or something like it. A large Jewish population is never purged from Judea in 70 AD after a rebellion. The province breaks away as Roman and later the Byzantine Empire crumbles and recedes. All of the land is eventually conquered as part of the Muslim Empire. Under the Muslim Empire, the Jews are protected by a system of tolerance through the transformation into the Ottoman Empire.
A royal family that serves in governance has presided over the Jewish homelands since ancient times. After World War I when the Jews rise up against the Ottomans as part of helping the British, they are in turn granted their independence as a free and sovereign kingdom. The monarchy eventually becomes ceremonial and based on a constitution, but remains in power until the modern day.
It's still hated by so many Arab states, especially for its support of the West in the Great War.