Spanish settlement in Argentina, that is the arrival of Spanish emigrants in Argentina, took place firstly in the period before Argentina's independence from Spain, and again in large numbers during the late 19th and early 20th centuries. Between the 15th and 19th centuries, the Spanish Empire was the sole colonial power in the territories that became Argentina after the 1816 Argentine declaration of independence. Thus, before 1816, a great part of the European settlers in Argentina were from Spain, and they carried the Spanish colonial administration, including religious affairs, government, and commercial business. A substantial Spanish-descended Criollo population gradually built up in the new cities, while some mixed with the indigenous populations (Mestizos), with the Black slave population (Mulattoes), or with other European immigrants.