The first great unification of the people came with the rise of the Quechua-speaking people, who ruled the Incan Empire. This improved communication and transportation, while also altering foods, dress, and other cultural aspects as Incan influence spread. However, this rule didn't destroy much of the past cultures so much as it melted aspects together while introducing new pottery, clothing, languages, and foods.
The culture and lifestyle was again altered with the arrival of the Spanish in the early 1500s. The Spanish took over the region and introduced numerous cultural aspects to the people including the Spanish language and Catholicism. Catholicism was adopted by most of the population, but the language and other cultural aspects from Spain were not as quickly accepted.
Unlike most of South & Central America, where Spanish influence dominated the local culture, in Bolivia the indigenous people continued to dominate the culture and lifestyle. The Spanish sought profits from the land's natural resources, but the high altitudes and many inaccessible areas left the Spanish focused in a couple cities. This allowed the local cultures to flourish then and even today as nearly half the people continue to speak an indigenous language.
Although Spain left its mark, particularly in the cities that arose under their rule, the indigenous people, particularly the Aymara and Quechua people continue to dominate the country culturally. Arguably the greatest impact the Spanish had on the country was in changing the lifestyle as the people today are more urbanized and regular jobs are more common, although many people remain in rural areas making a living off the land and by trading goods.