The transition to Christianity reduced the demand for frankincense.

Evidence

Arabian aromatics had powered the religious life of the pagan Roman Empire, but when that empire converted to Christianity and no longer needed frankincense for worship, the incense trade was dealt a massive blow, contributing to a collapse in the Yemen economy. — Neil MacGregor, A History of the World in 100 Objects, 714

Categorization

• corroborated: 2 independent passages support this claim — Neil MacGregor, A History of the World in 100 Objects, 714