In the 10th century, Howell the Good united the north and south of which country?

Hywel Dda, sometimes anglicised as Howell the Good, or Hywel ap Cadell (c. 880 – 948) was a king of Deheubarth who eventually came to rule most of Wales. He became the sole king of Seisyllwg in 920 and shortly thereafter established Deheubarth, and proceeded to gain control over the entire country from Prestatyn to Pembroke.

Hywel’s reign was remarkable for its peacefulness, the result of his consistent policy of subservience to England. Hywel’s first recorded act is his homage to Edward the Elder in 918. Thereafter, he often attended the English court, and his name is found as a witness to 12 charters of Athelstan and Edred between 928 and 949. In 928 he went to Rome on a pilgrimage.

Hywel was the only Welsh ruler to issue his own coins. He is remembered chiefly for the codification of Welsh law attributed to him. Although there is no contemporary record of this work, Hywel was certainly responsible for a coordination of preexisting law.