Why was the center of the Islamic Caliphate transferred from Medina to Kufa during the reign of Ali, may Allah be pleased with him?

Ali, may Allah be pleased with him, departed from Medina heading towards Shaam, then to Iraq, after learning of the departure of Talhah, Az-Zubayr, and Aishah, may Allah be pleased with them, to those regions. He then settled in Kufa due to its proximity to Shaam. As-Sallabi mentions that Medina was the capital of the state, and the situation changed after Ali's pledge of allegiance, as circumstances prompted him to leave Medina, especially after the aforementioned Companions departed for Iraq. The Companions in Medina did not support his departure, as he believed that the men and wealth were in Iraq. However, Abu Ayyub al-Ansari advised him to remain in Medina, considering it the fortified shield and the migration place of the Messenger of Allah, peace and blessings be upon him. Ali agreed with his opinion, but political developments forced him to leave Medina for Kufa to be close to the people of Shaam. Before his departure, he received news of Aishah, Talhah, and Az-Zubayr's departure to Basra.