Bible Tribes
Judah
Reuben
Gad
Asher
Naphtali
Manasseh
Simeon
Levi
Issachar
Zebulun
Joseph
Benjamin
Davidic Covenant
The Davidic Covenant is curious because of the unconditional nature of the covenant. Almost nowhere in the Christian world does anyone hunt down the people currently holding the covenant. This is a shame since it helps unravel other mysteries of the Bible.
Background
The covenant with David was unconditional. He would always have some descendent sitting on a throne over at least part of ancient Israel.
14 Jeremiah 33:19-26
19And the word of Yahvah came to Jeremiah saying,
20Yahvah says, If they can break my ordinances of the day, and my ordinances of the night, so that there should not be day and night in their appointed time;
21then my contract which I made with David my servant may also be broken, so that he should not have an heir to reign on his throne; and my contract with the priests and the Levites, my ministers.
22As the host of the skies cannot be numbered, nor the sand of the sea measured; so I will multiply the sons of David my servant and of the Levites who minister to me.
23Moreover, the word of Yahvah came to Jeremiah saying,
24Have you not considered what this people are saying, The 2 families which Yahvah has chosen, he has rejected? Thus they have provoked my people to anger, that they should not be a nation before me any longer.
25Yahvah says, If my contract not be in effect with day and night, and if I have not appointed the ordinances of the skies and land;
26then I will reject the sons of Jacob and of David my servant, so that I will not take any of his sons to be rulers over the house of Abraham, Isaac, and Jacob; for I will bring them back from their exile and will have mercy on them.
Jesus Not Yet in Fulfillment
When the angel appeared to Mary she was told that her son would sit on David's throne. Jesus eventually will do this. But... It hasn't happened yet. Nowhere in the New Testament does the crown of David get passed on to Jesus.
Strategy for Finding
Though this can probably be tracked forward from ancient times, it is easier to simply use a process of eliminiation. Which throne in the world today is likely David's throne?
Understand that nearly all of the royal thrones of Europe are inter-married so any answer from the European field means all thrones in Europe are David's throne.
Simple answer is the throne in the UK. This appears to be one of the key redemptive gifts of the British people. The current Queen rules over an empire that has stretched across about 1/2 of the world.