Article Usuage (gave a talk about; saw a new idea about)

[Kooiu]

Please help resolve this problem of article usage

1. The 1980s saw a new idea about the role of states in Asia

2. John gave a talk about blacks in America

3. Conflict in country A has recieved less attention

Can these sentences be rephrased as?
The 1980s saw a new idea about the role of states in Asia:
The 1980s saw a new idea about the role of states.
The states about which the new idea was found are in Asia

John gave a talk about blacks in America
John gave a talk about blacks
The blacks that John gave a talk about live in America

Conflict in country A has recieved less attention
There is an act of conflict in country A
The conflict has recieved less attention

Are "the role of states in Africa", "blacks in America" adjectival nouns, and "conflict in country A"
specific nouns
generic nouns
existential nouns
noun phraes
definite/indefinite noun phrases
adjectival nouns?

Why is that they are not definite: "the role of the states in Africa", "the blacks in America", and "the conflict in country A" given that the two sentences are about the class of states that are in Africa and the class of blacks that live in America.

Why is it that the three sentences do not go as follows:
The 1980s saw a new idea about the role of states in Asia
John gave a talk about the blacks in America
The conflict in country A has received less attention

Thank you