Did Arabs actually raise a red flag on the dome of their commander's marquee during the Haraam months?

Question

This answer to the question What is the purpose of putting a red flag on the dome of Hussain ibn Ali(as)'s shrine? states that if Arabs were at war with each other, during the Haraam months there would be a ceasefire (temporarily). To notify the opponent about it they would raise a red flag on the dome of their commander's marquee, and would resume thereafter.

Is that correct?

If so, how, when and why was this custom adopted?

Answer 1

Arabs before Islam raised the red flag on a tomb if the killer of the tomb owner had not been killed yet, and raised a black flag on the days when tomb owner was killed. This what Shia (Shiite) did until now on alhram months