The Bahá'í Faith is a diverse and widespread religion founded by Bahá'u'lláh in the 19th century in Iran. Bahá'í sources usually estimate the worldwide Bahá'í population to be above 5 million. Most encyclopedias and similar sources estimate between 5 and 6 million Bahá'ís in the world in the early 21st century. The religion is almost entirely contained in a single, organized, hierarchical community, but the Bahá'í population is spread out into almost every country and ethnicity in the world, being recognized as the second-most geographically widespread religion after Christianity. See Bahá'í statistics.