 Đại La was an ideal location for the new capital since it was on flatland and surrounded by rivers and lakes, which was advantageous for transportation, commerce, and military mobilization.In 1010, he issued a royal decree called Edict on the Transfer of the Capital for moving the imperial capital from Hoa Lư to Đại La.While travelling from Hoa Lư to the imperial settlement, he claimed to have had a vision of "a yellow dragon ascending" which inspired him to change the new settlement's name from Đại La to Thăng Long which means "Ascending Dragon".