Spanish (, ), also called Castilian (, ), is a Romance language that originated in the Castile region of Spain. Approximately 470 million people speak Spanish as a native language, making it second only to Mandarin in terms of its number of native speakers worldwide. There are an estimated 548 million Spanish speakers as a first or second language, including speakers with limited competence and 20 million students of Spanish as a foreign language. Spanish is one of the six official languages of the United Nations, and it is used as an official language by the European Union, the Organization of American States, and the Union of South American Nations, among many other international organizations. Spanish is a part of the Ibero-Romance group of languages, which evolved from several dialects of common Latin in Iberia after the collapse of the Western Roman Empire in the 5th century. It was first documented in central-northern Iberia in the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia. Since the early 16th century, Spanish was taken to the colonies of the Spanish Empire, most notably to the Americas, as well as territories in Africa, Oceania and the Philippines. From its beginnings, Spanish vocabulary was influenced by its contact with Basque, as well as by other Ibero-Romance languages, and later it absorbed many Arabic words during the Muslim presence in the Iberian Peninsula. It also adopted words from non-Iberian languages, particularly the Romance languages Occitan, French, Italian and Sardinian, as well as from Nahuatl and other Indigenous languages of the Americas. In modern times, it has continued to add its own new words, and has increasingly borrowed from English. Spanish is the official or national language of 19 countries in the Americas and totaling at least 418 million native speakers in the Hemisphere. Furthermore, Spanish is spoken fluently by 15% of all Europeans, making it the 5th-most spoken language in Europe. Spanish is the most popular language learned in the United States.