Why did Imam Hossein (AS) Leave Mecca towards Karbala?

While in Mecca, the Imam was visited day and night by many pilgrims who had come to Mecca for Umrah and Hajj. The Imam spoke to them about his intention for uprising against Yazid, but the Imam had limited support from the Meccans. Mecca was dominated by the Quraysh tribe, who had opposed the Prophet ever since he began his mission. The majority of them did not convert to Islam until after the conquest of Mecca by the Prophet. Furthermore, they had hatred towards Imam Ali, as the Imam had killed their relatives during their wars against the Prophet. When the people of Kufa found out that the Imam had not paid allegiance to Yazid and had migrated to Mecca, they decided to invite the Imam to Kufa, and pledged to support his uprising against Yazid. A flood of letters arrived to the Imam from Kufa. In just one day, the Imam received around 600 letters from Kufa, with a total of about 12,000 letters. The Imam had many Shia followers in Kufa and they had more political freedom. Kufa was a bigger city than Mecca or Medina, with a larger population and potential for troops. It was the main center of opposition to the Umayyads since the caliphate of Imam Ali. Thus, the Imam sent his cousin, Muslim ibn Aqeel, to investigate whether the Kufans were sincere in their intentions.To fulfill his responsibilities, the Imam also sent letters to the tribal leaders of Basrah to ask for their support. Unlike the Kufans, the people from Basrah had not contacted the Imam prior to this. Only a small group of people from Basrah joined the Imam. One recipient of the Imam’s letter took the letter to Ibn Ziyad, the governor of Basrah. In response, the governor ordered to kill the Imam’s messenger, Sulayman ibn Razin, who became the first martyr of the Imam’s uprising. Muslim ibn Aqeel arrived in Kufa and 18,000 people paid allegiance to him on behalf of the Imam. He informed the Imam of this, and asked him to come towards Kufa immediately. People were continuously coming to Muslim for giving allegiance and a total of up to 40,000 people paid allegiance. After receiving the letter from Muslim, the Imam left Mecca in the darkness of dawn on the 8th of the month of Zu al-Hijjah, one day before the Hajj pilgrimage started. This day coincided with the day of Muslim’s uprising and defeat in Kufa. The Imam left Mecca as he verified news that Yazid was planning his assassination while the pilgrims would be performing Hajj, and would not be carrying any weapons. The Imam did not want his blood to be shed in the vicinity of the Holy Ka’ba due to the sanctity of the holy site. The Imam told some people that he preferred that his blood be shed outside, as opposed to inside the holy site’s vicinity. Thus, the Imam left Mecca with a caravan, whose count is estimated by some to be about 130 people, after staying there for four months and five days.