Is it possible for the Great Dajjal (Antichrist) to be born after the death of Prophet Muhammad (peace and blessings be upon him), or must he have been in existence before that, and what is the evidence for each of these two matters?

The Dajjal was born and has existed since the time of the Prophet, peace and blessings be upon him, as is established in Sahih Muslim in the hadith of Fatimah bint Qais from the Prophet, peace and blessings be upon him, known as the Hadith of Al-Jassasah. Tameem Ad-Dari reported that the Dajjal is confined in a monastery on an island. The Prophet, peace and blessings be upon him, described him to the Companions, and the Dajjal informed Tameem that he would emerge and roam the Earth except for Makkah and Madinah, as they are forbidden to him.