The Kingdom of the Winds (2008)

Because they are both period drama's. They both have another similarity, which is prophecy. Other than that not much is alike, but they are both good.

It's the sequel to Jumong - following the journey of Jumong's grandson

Both are historical dramas.
Both dramas have revenge and prophecies related to the protagonists and the overthrow of the throne.

=> Both are dramas set in Three Kingdoms of Korea
=> Both main characters eventually became rulers
=> Both main characters were born with a bad omen, thus they had to live away from the palace in order to be not killed
=> Both main characters returned to claim their title as prince/princess when they got older.
=> Both main characters have an older sibling that loves and protects them

The story of the prince that grows as a commoner without knowing his identity is very very similar. He lives a very hard life. At some point, he gets kicked to the enemy’s country. He also falls for a woman from the enemy. Bonds with his real brother without knowing whom he is. In both dramas, the fate of many characters around him is the same. At the end, becomes the king (according to historical facts).

Both dramas staring Song Il Gook. Both rags to riches kind of story. Both characters has a loyal side kick from since childhood. Both have forbidden love with a princess.