Jacques Ryckmans, who deciphered the Sabaean inscriptions, writes in his "La Persécution des Chrétiens Himyarites", that Sarah'il Yaqbul-Yaz'an was both the tribal chief and the lieutenant of Yusuf 'As'ar (the king) at the time of the military campaign, and that he was sent out by the king to take the city of Najran, while the king watched for a possible Abyssinian/Ethiopian incursion along the coastal plains of Yemen near Mokhā (al-Moḫâ) and the strait known as Bāb al-Mandab. It is to be noted that the Ethiopian church in Ẓafar, which had been built by the Himyarite King some years earlier following the proselytizing mission of Theophilos the Indian and another church built by him in Aden (see: "Ecclesiastical History of Philostorgius", Epitome of Book III, chapter 4), had been seen by Constantius II during the embassage to the land of the Ḥimyarites (i.e. Yemen) in "circa" 340 CE. This church was set on fire and razed to the ground, and its Abyssinian inhabitants killed. Later, foreigners (presumably Christians) living in Haḏramawt were also put to death before the king’s army advanced to Najran in the far north and took it.