Well, the Hijri date 20 Shaban 1290 corresponds to the Gregorian date Sunday, 12 October 1873. This date lies in the eighth month of the Hijri year 1290 AH, which is Shaban of 1290 AH. Both this Hijri and Gregorian date occur on the single day that is Sunday without any doubt. The Arabic date 1290/08/20 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 12 October 1873 to its equivalent Arabic date.
The following is the conversion of the Arabic date 20 Shaban 1290 AH to its equivalent Gregorian date.
يَحْسَبُونَ ٱلْأَحْزَابَ لَمْ يَذْهَبُوا۟ ۖ وَإِن يَأْتِ ٱلْأَحْزَابُ يَوَدُّوا۟ لَوْ أَنَّهُم بَادُونَ فِى ٱلْأَعْرَابِ يَسْـَٔلُونَ عَنْ أَنۢبَآئِكُمْ ۖ وَلَوْ كَانُوا۟ فِيكُم مَّا قَٰتَلُوٓا۟ إِلَّا قَلِيلًۭا
They hold that the clans have not retired (for good); and if the clans should advance (again), they would fain be in the desert with the wandering Arabs, asking for the news of you; and if they were among you, they would not give battle, save a little.
Surah Al-Ahzaab(33:20)