Who are Shias?

There were no such thing as Ahle Sunnah or Sunnis at the time of Imam Husain(a.s) . Also there was no such thing as Shia Isna Ashari or any other Shia sect at that time. It was Muslims all the way through. Everything kicked off later on after the Prophet's [pbuh] death. First the Muslims were divided into two groups. Those who selected and accepted Hazrath Abu Bakar [ra] as the first Khalif of the Muslims were known as just Muslims. They had nothing to do with Ahle Sunnah or being Sunni because Ahle Sunnah didn't start to develope until Imaam Abu Hanifa's time. From there on Sunnis start to form and other Ahle Sunnah groups started to emerge. Those people who opposed the meeting in Sakeefa and rejected the appointment of any Khalif by the Ummah because they believed that the Prophet [pbuh] named, nominated and appointed his successor, like every great leader does which was Hazrath Ali [ra], were later on named as Shiayaan-e-Ali [ra]. This is were the Shia, with the ideology of Khilaafath-e-ilahiya, started to develope. This was the birth point of the main stream Shia of today. Also the term Shia was used in general. Shia means follower/supporter. This term was used for everyone on common grounds for example: during the battle of Jamal and Safeen the common Muslims were also divided into two groups. Shia-e-Ali [ra] and Shia-e-Aisha [ra] during the Battle of Jamal then Shia-e-Ali [ra] and Shia-e-Muavia during the battle of Safeen.  The situation is the same when it comes to Hazrath Hassan [ra] and Ameer Muavia or Hazrath Hussain [ra] and Yazeed. The followers and supporters of each and everyone was known as a Shia. So when you talk about Shia regarding history it depends on who's Shia you are talking about. It was the Muslims who accepted Hazrath Abu Bakar [ra] as the first Khalif. It was the same Muslims who accepted Hazrath Umar [ra] as the second Khalif. It was the same Muslims who accepted Hazrath Usmaan [ra] as the third Khalif. It was the same Muslims who pesterd and persuaded Hazrath Ali [ra] to become the fourth Khalif when no one dared to take on Khilaafath after the murders of the previous two Khalifs. It was the same Muslims who betrayed Hazrath Ali [ra] during the battles of Jamal and Safeen. It was the same Muslims who pesterd and persuaded Hazrath Hassan [ra] to become the fifth Khalif of the Muslims and later on betrayed him by joining the camp of Ameer Muavia or refusing to fight him. It was the same Muslims who accepted Ameer Muavia as the sixth Khalif and Yazeed as the seventh. It was the same Muslims who informed Hazrath Hussain [ra] of Yazeed's intentions and ways regarding the Quran and Sunnah. It was the same Muslims who promised aid and support to Hazrath Hussain [ra] and invited him. It was the same Muslims who let Hazrath Hussain [ra] and his companions down for example Hazrath Muslim bin Aqeel [ra] etc by being afraid of standing up to Yazeed's governers, companions, army etc and by being afraid of Yazeeds response.