Letters of invitation to Islām, which were dispatched at this instance, were addressed to the rulers of the four corners of Arabia. That is to say, in the North, to Caesar, ruler of the renowned Kingdom of Rome and in the North East, to Chosroes, ruler of the renowned Kingdom of Persia. Then, in the South west of Arabia, to Maqauqis, King of Egypt.1 In the East, to Ḥaudhah bin ‘Alī the Chieftain of Yamāmah and in the West, to the Negus, King of Abyssinia, which was a Christian government in the continent of Africa, situated directly opposite Arabia. Then, in the South, adjoining the boundary of Arabia, to the Governor of Ghassān who was subservient to Caesar. Similarly, the Holy Prophet(sa) sent a letter to the south of Arabia, addressed to the Chieftain of Yemen and another letter to the East of Arabia to the Governor of Baḥrain, etc.2 In this matter, the Holy Prophet(sa) fulfilled the duty of preaching by conveying the message of Islām to the four corners of Arabia. However, one should not think that all these letters were dispatched immediately after the Treaty of Ḥudaibiyyah. It is possible that certain letters were sent out at one time, while some were dispatched after some time. However, in any case, it is a confirmed act that they began to be sent out after the Treaty of Ḥudaibiyyah. However, the first letter was perhaps dispatched and addressed to the Caesar of Rome, i.e. to Heraclius, and we begin this note with him.
1 In actuality, “Maqauqis” was the name of the office of the governor of Egypt and every governor was referred to as “Maqauqis.” In that era, these governors of Egypt were subservient to Caesar of Rome. However, perhaps this was an inherited position, which except in special circumstances, remained within one distinct family. The Arab people would refer to such leaders as ‘Malik’ i.e., King as well.
2 As-Sīratun-Nabawiyyah, By Abū Muḥammad ‘Abdul-Mālik bin Hishām, pp. 869-870, Dhikru Jumlatil-Ghazawāt/Khurūju Rusūli Rasūlillāhi Ilal-Mulūk, Dārul-Kutubil-‘Ilmiyyah, Beirut, Lebanon, First Edition (2001)
Sharḥul-‘Allāmatiz-Zarqānī ‘Alal-Mawāhibil-Ladunniyyah, By Allāmah Shihābuddīn Al-Qusṭalānī, Volume 5, pp. 4-5/14/19-20/27/34/37/43/46, Wa Ammā Mukātabatuhū ‘Alaihiṣ-Ṣalātu Was- Salāmu Ilal-Mulūki Wa Ghairihim, Dārul-Kutubil-‘Ilmiyyah, Beirut, Lebanon, First Edition (1996)
Tārīkhul-Khamīs Fī Aḥwāli Anfasi Nafīs, By Ḥusain bin Muḥammad bin Ḥasan, Volume 2, pp. 29- 31/34/37-39, Irsālur-Rusula Ilal-Mulūki, Mu’assasatu Sha‘bān, Beirut
The Life of Mahomet, By Sir William Muir, Chapter XX, Embassies to Various Sovereigns and Prices, pp. 382-387, Published by Smith, Elder & Co. London (1878)