Choi Su-jong

Depicting the afflictions of youth, First Love is the story of two brothers who fall for the same woman. It is currently the highest-rated Korean drama of all time. (wikipedia)

Jang Bo Go (Choi Soo Jong) was a slave from Shilla (a Korean dynasty that lasted from 57 B.C. until 935 A.D.) He was sold in China during the Tang Dynasty, where he was trained as a gladiator-slave. Through hard work and perseverance, he made it back to Shilla and became a successful sea merchant. The sea passage at the time was plagued by pirates and Jang Bo Go went head to head with them in battles and managed to keep the pirates at bay. (imdb)

The drama tells the story of the life of Dae Jo-yeong, also known as the founder of the kingdom of Balhae, from birth to his death. (imdb)