Why was it relatively convenient for the disciples to travel in the Roman Empire? Christians made good use of the Roman system of roads.
فَٱسْتَطَاعَ ٱلْمَسِيحِيُّونَ أَنْ يُسَافِرُوا بِٱلْمَرَاكِبِ لِيَصِلُوا إِلَى كُلِّ أَنْحَاءِ ٱلْإِمْبَرَاطُورِيَّةِ ٱلرُّومَانِيَّةِ .‏