A group from the east will prepare the way for the coming of Hazrat Mahdi (as)

Some people will come from the East and prepare the sultanate of Hazrat Mahdi (as). (Ibn Hajar al-Haythami, Al-Qawl al-Mukhtasar fi `Alamat al-Mahdi al-Muntadhar , p. 21)

A community will come from the East and assist the sultanate of Hazrat Mahdi (as). (Al-Muttaqi al-Hindi, Al-Burhan fi Alamat al-Mahdi Akhir az-Zaman, p. 60)

... They will come down to Jerusalem and prepare the sultanate for Hazrat Mahdi (as). (Ibn Hajar al-Haythami, Al-Qawl al-Mukhtasar fi `Alamat al-Mahdi al-Muntadhar, p. 47)