“Historically” and “different conceptions”

Historically

Here means:

at different points in historical time, rather than always having the same conception.

For example, the United States did not maintain one unchanging legal conception of citizenship from the eighteenth century onward.

There were major transformations involving:

slavery;

emancipation;

Reconstruction;

citizenship;

voting;

racial exclusion;

civil rights.

Different conceptions

Means:

different understandings of who qualifies as a full member of the political community and what rights or status that membership entails.

For example, a system can recognize:

Person A is the full political member

while treating:

Person B is the legally subordinate or excluded.

Those classifications can change historically.