The cultures of the Celtic and Iberian populations were gradually Romanised (Latinised) at different rates depending on what part of Hispania they lived in, with local leaders being admitted into the Roman aristocratic class. Hispania served as a granary for the Roman market, and its harbours exported gold, wool, olive oil, and wine. Agricultural production increased with the introduction of irrigation projects, some of which remain in use. Emperors Hadrian, Trajan, Theodosius I, and the philosopher Seneca were born in Hispania. Christianity was introduced into Hispania in the 1st century CE and it became popular in the cities in the 2nd century CE. Most of Spain's present languages and religion, and the basis of its laws, originate from this period.