After the demise of Hazrat Ismaa‘eel (‘alaihis salaam), his son, Qaydaar, assumed the role of trustee of the Ka’bah. This was in accordance with his parting advice. In this manner, the Banu Ismaa‘eel (the progeny of Hazrat Ismaa‘eel (‘alaihis salaam)) remained the trustees of the Ka’bah.
As time passed, however, hostilities and aggression erupted between the Banu Ismaa‘eel and the Banu Jurhum. In due course, the Banu Jurhum prevailed and subsequently established their rule over Makkah Mukarramah. Before long, the Jurhum rulers had unleashed their aggression, tyranny and cruelty over the people of Makkah Mukarramah. This ruthless brutality drove the Banu Ismaa‘eel out of Makkah Mukarramah and forced them to settle on its outskirts.
When the brutal tyranny, immorality and disrespect of the Banu Jurhum for the Baytullah surpassed all bounds, all the Arab tribes united to challenge them and bring an end to their transgressions. As a consequence, the Banu Jurhum were compelled to flee from Makkah Mukarramah. However, as they were departing from Makkah Mukarramah, they buried a number of relics of the Ka’bah in the well of Zam Zam. They thereafter filled it with sand until they brought it level to the ground in such a manner that no sign of the well could be detected.
After the evacuation of the Banu Jurhum, the Banu Ismaa‘eel returned to Makkah Mukarramah and settled down, but did not turn their attention to the well of Zam Zam. With the passage of time, not a single trace of the well remained and it fell into total oblivion.
(Extracted from Seeratul Mustafa 1/34)