She had been married to Ibn Jahsh, who died while she was with him. He was among those who had migrated to the land of Abyssinia. Negus then gave her in marriage to the Messenger of Allah ﷺ while she was still among them.
حدثنا محمد بن يحيى بن فارس حدثنا عبد الرزاق عن معمر عن الزهري عن عروة بن الزبير
أنها كانت عند ابن جحش فهلك عنها وكان فيمن هاجر إلى أرض الحبشة فزوجها النجاشي رسول الله ﷺ وهي عندهم
[Its chain is daif] Nasai narrated it in the Book of Marriage, Chapter on Fairness in Dowries, no. 3352, from the hadith of Mamar, with this wording. The hadith has many corroborating witnesses. Zuhri is a mudallis and he narrated it using "an" (indicating possible concealment in the chain).