There is a famous story that a Companion of Prophet Muhammad, sallallaahu 'alayhi wa sallam, named Tameem Ad-Daari, may Allah be pleased with him, met the Dajjaal (the Antichrist) during his journey to an unknown island in the east where he interacted with him and they spoke and a long interaction took placed between them. So the Dajjaal was answering his questions in Arabic, so does he understand that language, or does he belong to the Arabs too, because in order to learn the language, he must have had someone close by him who could teach him the Arabic language to enable him to talk? Does he belong to the Arabs? Was he born to Arab parents? Is there any evidence that was narrated by that Companion of the Prophet?

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger. 

The story that you referred to was reported in an authentic hadeeth in Saheeh Muslim, and we mentioned it in fatwa 346750, so please refer to it.

It is obvious from the story that the Dajjaal spoke to Tameem Ad-Daari in Arabic. As for your question as to whether he is an Arab and whether he was born to Arab parents etc., then we are not aware of this, and we have not come across an authentic text that clarified this.

However, the fact that he spoke in Arabic does not necessarily mean that he is an Arab or that there was an interpreter with him.

Indeed, there are many non-Arabs who speak Arabic, as is known. And even if we were to presume that he is not an Arab and does not know Arabic, perhaps the Dajjaal was inspired (by Allah) to speak Arabic in this story. In this hadeeth, the Dajjaal said, "Tell me about the Prophet of the illiterate; what did he do? ... and so on. It may be understood from this that he is not an Arab, and by ‘the illiterate’, he means the Arabs, as they were illiterate and did not know how to write or read.

Allah says (what means): {It is He Who has sent among the unlettered a Messenger from themselves…} [Quran 62:2]

Also, according to view that Ibn Sayyaad is the Antichrist, then Ibn Sayyaad was Jewish from the Jews of Madeenah, and he was not from an Arab descent.

In any case, investigating such matters does not result in any action, and there is no benefit in knowing whether the Dajjaal is an Arab or a non-Arab. Nevertheless, the Sunnah clarified that the Arabs will be few in number at the time of the Antichrist.

Umm Shareek, may Allah be pleased with her, narrated that the Prophet said, "Verily, the people will flee from the Dajjaal to the mountains." Umm Shareek asked, "O Messenger of Allah! Where will the Arabs be then?" He said, "They will be few." [Muslim]

What is important is that the Muslim takes the means that protect him from the trial of the Dajjaal. The Prophet taught us how to protect ourselves from him, such as seeking refuge in Allah from him, fleeing from him if one is alive when the Dajjaal emerges, and reciting the verses at the beginning of Soorah Al-Kahf [verses 1-10]

Allah knows best.