Well, the Hijri date 12 Rabi Al Thani 1255 corresponds to the Gregorian date Monday, 24 June 1839. This date lies in the fourth month of the Hijri year 1255 AH, which is Rabi Al-Thani of 1255 AH. Both this Hijri and Gregorian date occur on the single day that is Monday without any doubt. The Arabic date 1255/04/12 is calculated using the Umm Al-Qura calendar and the sighting of the moon. One thing to remember is that this Arabic date may occur on different Gregorian date depending upon the region and country and obviously the moon.
If you are still not sure about the date then you can use our Arabic date converter.
The following is the conversion of the Gregorian date 24 June 1839 to its equivalent Arabic date.
The following is the conversion of the Arabic date 12 Rabi Al Thani 1255 AH to its equivalent Gregorian date.
أَفَأَمِنَ أَهْلُ ٱلْقُرَىٰٓ أَن يَأْتِيَهُم بَأْسُنَا بَيَٰتًۭا وَهُمْ نَآئِمُونَ
Are the people of the townships then secure from the coming of Our wrath upon them as a night-raid while they sleep?
Surah Al-A'raaf(7:97)