The Byzantine Empire

In the introduction to The Sealed Nectar, the Romans were the imperial power ruling Egypt, Syria and northern Hijaz. They controlled the sea trade routes, were the patrons of the Arab allies in Syria, and incited the Abyssinians against Yemen ^{1 2 3}.

Yemen's trade failed as the Romans prevailed over the sea trade routes after extending their power over Egypt, Syria and northern Hijaz. Their occupation of Egypt and Syria also disrupted the overland route. This was among the causes of the migration of the Kahlan clans ^{1 2}. The Romans destroyed the Nabataeans ⁴.

The Romans entered Aden, and with their help the Abyssinians occupied Yemen for the first time in 340 CE ². After the Ditch of Najran, the Roman emperors incited the Abyssinians and prepared a naval fleet for them, and they occupied Yemen in 525 CE ^{2 5}.

The Romans made the Dajaima and then the Ghassanids kings over the Arabs of Syria. They did this to restrain the desert Arabs and to serve as a force against the Persians, until the Battle of Yarmouk in 13 AH ³. Persian kings feared the Romans, and kept the Arabs of Iraq opposite the Arabs of Syria ⁶. Christianity entered the Arab lands through the Abyssinian and Roman occupations. The Ghassanids embraced it, and so did Taghlib and Tayy because of their proximity to them ^{7 8}. The author notes that the Roman occupation of Palestine in 70 CE and the destruction of the Temple was the second wave of Jewish migration to the Hijaz ⁷.

The Prophet's letter to Heraclius, and the battles of Mu'ta and Tabuk, are presented in their own entries.