Dhritarashtra was born blind. But he belonged to the powerful Kuru clan, therefore, it was easy for him to find a bride. Then, why was Gandhari chosen to marry the blind Dhritarashtra? There is a reason for this choice and it is associated with a boon to Gandhari by Lord Shiva.
Pandu married Kunti and Madri. But he did not have any children in both the wives.
Bhishma then heard about Gandhari, the daughter of Subala, the king of Gandhara. Gandhari was famous for her beauty and virtue. But even more famous was her devotion to Lord Shiva.
By her intense austerities and unshakable devotion and faith, she had obtained a boon from Shiva to be the mother of 100 sons.
Bhishma who was eager to ensure the continuity of Kuru clan sent his ambassadors to the Gandhara king, proposing his daughter’s marriage with Dhritarashtra. King Suvala knew Dhritarashtra was blind but assented to the match, as he did not want to miss the opportunity of getting a powerful n ally like the Kuru dynasty.
Thus, Bhishma was keen on getting Gandhari as the wife of Dhritarashtra to ensure the continuity of the Kuru Dynasty. King Suvala sacrificed his daughter to become a powerful king.