The Prophet ﷺ said, "I saw (in a dream) a black woman with unkempt hair going out of Medina and settling at Mahai'a, i.e., Al-Juhfa. I interpreted that as a symbol of epidemic of Medina being transferred to that place (Al-Juhfa).  

أَنَّ النَّبِيَّ ﷺ قَالَ رَأَيْتُ كَأَنَّ امْرَأَةً سَوْدَاءَ ثَائِرَةَ الرَّأْسِ خَرَجَتْ مِنَ الْمَدِينَةِ حَتَّى قَامَتْ بِمَهْيَعَةَ وَهْىَ الْجُحْفَةُ فَأَوَّلْتُ أَنَّ وَبَاءَ الْمَدِينَةِ نُقِلَ إِلَيْهَا