Why was it difficult for places like India or Latin America to be united unto themselves?

It was, and is, hard for places like India and Latin America to be truly united because there are too many differences between the people in various parts of these places.  These differences can be ethnic and/or economic.

Both India and Latin America are made up of regions with people of different ethnicities.  It is true that most of Latin America (with Brazil being the main exception) is Spanish-speaking.  However, the different countries of Latin...

It was, and is, hard for places like India and Latin America to be truly united because there are too many differences between the people in various parts of these places.  These differences can be ethnic and/or economic.

Both India and Latin America are made up of regions with people of different ethnicities.  It is true that most of Latin America (with Brazil being the main exception) is Spanish-speaking.  However, the different countries of Latin America do have major ethnic differences between them and in some cases within them.  The indigenous people of Bolivia, for example, do not speak the same language as the indigenous people of Mexico (who do not all speak the same language either).  As another example, Argentina has many more people of European descent than many other Latin American countries.

While India is now one country, it is a huge country that was not really united until independence.  According to the link below, India today has 13 languages that have at least 10 million native speakers. The country also has significant religious minorities that do not always get along with the majority religion.

There are also economic differences between countries and regions.  For example, the CIA Factbook also tells us that the per capita GDPs of Chile and Argentina are both between four and five times higher than that of Honduras even though all three countries are part of Latin America.  There are also huge differences in wealth today between various Indian states.

For these reasons (along with reasons like the size of these regions and the historical difficulty of travelling within them), places like India and Latin America have had a very difficult time trying to unite.