Some historical facts about the Ḥajr Aswad (Black Stone) in the Ka'bah
by Yassir qadhi
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Theologically, from the ḥadith we learn that Jibrīl brought this stone to Ibrahīm from Jannah, and that it was originally white.
When the ancient tribe of Jurham was expelled from Makkah (before the time of Jesus, some millennia before Islam), they took the Ḥajr and hid it; however Allah willed that a lady from the tribe of Khuzā`ah saw this from afar and told her tribe where it was hidden. Hence they dug it back and replaced it.
It is possible it was first broken during this time - sources are vague.