“You will be my witnesses in Jerusalem, in all Judea and Samaria, and to the end of the earth.”
— Acts 1:8
Geography does a great deal of work in these articles. The gospel reached Persia before it reached England; three of the greatest early theologians were African; the churches of Syria and Egypt were older than anything in Europe and are largely gone. Those sentences land differently when you can see them.
Coastlines, lakes and rivers come from Natural Earth, which is in the public domain — the same reason the Scripture text throughout this site is the World English Bible. Cities are placed by coordinate. Frontiers and shaded areas are generalised, because the things they describe moved from decade to decade and were frequently zones rather than lines; each caption says where that applies.
The land of the Gospels, c. AD 30. Almost everything in the four Gospels happens inside about 120 miles north to south — Nazareth to Jerusalem is roughly a four-day walk. Regional boundaries shifted with each Herodian settlement and are shown approximately.
The world the gospel was born into, c. AD 30–60. One empire, one road network and one trade language from Spain to Syria — and, just beyond the Euphrates, a rival empire Rome never subdued. Frontiers are generalised: Rome's eastern border in particular was a contested zone rather than a line, and it moved repeatedly within these decades.
Paul's journeys, AD 46–60. Roughly 10,000 miles, most of it on foot or on other people's cargo ships, over about fourteen years. Routes join the places Acts names in the order it names them; the actual roads and sea lanes curved around mountains and weather.
Where the church had reached: AD 100, AD 300, AD 600. Each dot marks a place with evidence of a Christian community by that date — a New Testament letter, a named bishop, a martyr account, a council signature. Absence of a dot means absence of surviving evidence, not absence of Christians. The frame stops at Merv: by AD 635 the Church of the East had reached Xi'an in China, and Christians were established on the Malabar coast of India well before that. Both are off this map, which is itself the point.
The map changes: the Arab conquests to AD 750. Within a century of Muhammad's death in 632, the heartlands of Christianity — Syria, Palestine, Egypt, Mesopotamia, North Africa and Persia — were under Muslim rule. What changed first was the political map, not the religious one: these lands stayed majority-Christian for generations, and the Church of the East went on sending missionaries to China from inside the caliphate. Conversion came slowly, over centuries, under legal and fiscal pressure. Frontiers are generalised and were in constant motion.