He shall judge between the nations,
and shall decide for many peoples;
and they shall beat their swords into plowshares,
and their spears into pruning hooks;
nation shall not lift up sword against nation,
neither shall they learn war any more. (Isaiah 2:4)
If we've been experiencing world peace for the past 2000 years, I must have missed it.
upon the throne of David
Jesus never sat upon the throne of David.
This Prophetic Scripture you have quoted will be fulfilled when Jesus, the Messiah returns as the conquering Messiah.
The Gospel of Matthew, Ch. 1
The book of the generation of Jesus Christ, the son of David, the son of Abraham, {Genesis 12:3}, (2)Abraham begat Isaac; and Isaac begat Jacob; and Jacob begat Judas and his brethren; {Genesis 28:14) (3)And Judas begat Phares and Zara of Thamar; and Phares begat Esrom; and Esrom begat Aram; (Genesis 38:27 + Ruth 4:18) (4) And Aram begat Aminadab; and Aminadab begat Naasson; and Naasson begat Salmon; (5) And Salmon begat Booz of Rachab; and Booz begat Obed of Ruth; and Obed begat Jesse; (6) And Jesse begat DAVID the king; and David the king begat SOLOMON of her that had been the wife of Orias;(1 Sam. 16:1) (7) And Solomon begat Roboam; and Roboam begat Abia and Abia begat Asa (1 Chr. 3:10); (8) And Asa begat Josaphat; and Josaphat begat Joram; and Joram begat Ozias (2 Kings 15:13) (9) And Ozias begat Joatham; and Joatham begat Achaz; and Achaz begat Ezekias; (10) And Ezekias bebat Manasses; and Manasses begat Amon; and Amon begat Josias (2 Kings 20:2); (11) and Josias begat Jechonias and his brethern, about the time they were carried away to Babylon; (2 Kings 24:14-16) (12) And after they were brought to Babylon, Jechonias begat Salathiel; and Salathiel begat Zorobabel; (1 Chr. 3:17) (13) And Zorobabel begat Abiud; and Abiud begat Eliakim; and Eliakim begat Azor; (14) And Azor begat Sadoc; and Sadoc begat Achim; and Achim begat Eliud; (15) And Eliud begat Eleazar; and Eleazar begat Matthan; and Matthan begat JACOB; (16) and JACOB begat JOSEPH the HUSBAND OF MARY, of whom was born Jesus, who is called Christ.
(17) So all the generations from Abraham to David are fourteen generations; and from David until the carrying away into Babylon are fourteen generations; and from the carrying away into Babylon unto Christ are fourteen generations(2 Kings 24:14)