Ubayd Allah ibn Ziyad
There are no historical records of Kumayl during the period between 40 AH (660 CE) to 80 AH. After the martyrdom of Imam Ali, Kumayl suddenly disappeared for 40 years. High scholars have no clue as to where he was during these years. He is not mentioned in any major events, including the Event of Ashura, nor is he mentioned after that event, until 80 AH. However, there is a theory that Kumayl was imprisoned by Governor Ubayd Allah ibn Ziyad (no blood relation of Kumayl), because there are historical records of a person named Kumayl al-Hamadan'i, who was imprisoned by Ubayd Allah ibn Ziyad. The title al-Hamadan'i is given to a person from the tribe of Hamadan of Yemen. The Hamadan tribe was one of the four major tribes of Yemen and was closely linked to the Banu Nakha tribe - the tribe that Kumayl ibn Ziyad is from, hence his title al-Nakha'i. The theory is that the historical records might have misspelled, or misinterpreted, or misunderstood, or confused Kumayl's title, so that Kumayl al-Hamadan'i was actually Kumayl al-Nakha'i (Kumayl ibn Ziyad).