All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
Imaam Ibn Katheer reported from Al-Hassan Al-Basri in the explanation of the verse (which means) {And We said, “Go down, [all of you], as enemies to one another, and you will have upon the earth a place of settlement and provision for a time.”}[Quran 2:36] he said, 'Aadam, was brought down in India, Eve, may Allaah exalt her mention, in Jeddah, Iblees in Bidasteesaan next to Basrah and the snake in Asfahaan.'
The snake here is the one who is mentioned in the books of the People of the Book that it guided Eve, may Allaah exalt her mention, to the tree. It was a beautiful snake….
All the above matters are not proved in any sound narration. There is no sound narration, according to our knowledge, that specifies the places where Aadam, his wife, may Allaah exalt their mention, and Iblees were brought down. Also, there is no sound narration that mentions the snake. Therefore, Imaam Ibn Katheer wrote in the explanation of Chapter Al-A'raaf: 'If the mention of the snake is correct it is pursuant to Iblees. The scholars who explained the Quran have determined the places where they were brought down but the origin of all these narrations was the sources of the People of the Book, Allaah Alone Knows the authenticity of such narrations. If there was any benefit for human beings, in this life or in the next life, in mentioning the names of those places, Allaah would have mentioned in His Book or His Prophet would have mentioned it.'
In short, there is no benefit in this knowledge, and a Muslim should not make himself and others busy in useless matters.
As for the narration you are asking about, Hakeem Ibn Mu'aawiyah narrated from his father that the Prophet said: "You are the seventieth nation, but you are the best and most honorable of them to Allaah." It is a sound narration.
It means that there will be sixty nine other nations on the Day of Judgment and the Muslim nation will be the seventieth one. And this (Muslim) nation will be the best of all these nations. This virtue is also mentioned in the Quran. Allaah Says (which means): {You are the best nation produced [as an example] for mankind.}[Quran 2:110].
Allaah Knows best.