When Shakuni resided for too many years in Hastinapur, who looked after his empire in Gandhar? Don't go by the script of television series. Shakuni was son of Subala of Gandhar, who was the king. Unlike misguiding narratives, Shakuni’s father and brothers weren't killed by Bhishma. Instead, Subala was very much alive, who also attended Yudhishthira's Rajasuya yagna. Shakuni never stayed permanently in Hastinapur. 'O descendant of the Bharata lineage! All of them were welcomed with honour--Dhritarashtra, Bhishma, the greatly intelligent Vidura, all the brothers with Duryodhana at the forefront, all the kings with the preceptor at the forefront, Subala the king of Gandhara, the immensely strong Shakuni, Achala, Vrishaka, the supreme warrior Karna, Rita, Shalya the king of the Madras, the maharatha Bahlika, Somadatta of the Kuru lineage, Bhuri, Bhurishrava, Shala, Ashvatthama, Kripa, Drona, Jayadratha the king of Sindhu, Yajnasena and his son, Shalva the lord of the earth… Chapter 256 (31), Rajasuya Parva, Section 24, Mahabharat On the other hand, his brothers (not 100 but 6) were killed during the battle. They fought from Kaurava side. Now coming to the answer, Shakuni never stayed permanently in Hastinapur. He was a usual visitor and guest. Ved Vyasa didn't find it necessary to add Shakuni’s duties and acts as the prince of Gandhar. Firstly, it wasn't necessary in the plot and added no actual weight to the script. Secondly, the epic's prime focus was showcasing the battle between cousins. Shakuni's presence in Hastinapur Surely there were a lot more things which happened in Hastinapur, but not every single detail is accounted in the epic. Only the major ones which were crucial for the narrative are added in the epic. Thus, as in most of the scenes between Shakuni and Duryodhana and his gang happen in Hastinapur, it seems Shakuni was always present in Hastinapur. In reality, the narrative where Shakuni is seen administering Gandhar, was not deemed necessary for the plot of Mahabharat. As for the administration of Gandhar was taken care by Subala who was the king. He was very much alive and not killed by Bhishma by starvation. Only necessary events which included Shakuni's presence in Hastinapur have been added, which doesn't mean he was permanently present in Hastinapur.