grammar ok?

[ostap77]

The 20th century isolationism had surely been rather symbolic and was being implemented in politics under the influence of a very peculiar situation that had arisen in the world.

[Raymott]

The 20th century isolationism was had surely been rather symbolic and was being implemented in politics under the influence of a very peculiar situation that had arisen in the world.

There's no reason for the past perfect in the first clause. In fact, the simple past here works better with the use of the past perfect in the last clause.

[ostap77]

There's no reason for the past perfect in the first clause. In fact, the simple past here works better with the use of the past perfect in the last clause.

1)The reason I used the past perfect was to mean that action started at a certain point in the past and continued till the beginning of the 21st century. So there are no reasoned grounds to use the past perfect in the first clause?

2)Could I say "was being implemented in politics ......" to mean ongoingness of a process since I can't tell if it was implemented or not?

[bhaisahab]

The reason I used the past perfect was to mean that action started at a certain point in the past and continued till the beginning of the 21st century. So there are no reasoned grounds to use the past perfect in the first clause?

No, there is no need for the past perfect in the first clause. Had you mentioned a period of time up to the beginning of the 21st century, seen from the present day, it might have been appropriate.

[ostap77]

No, there is no need for the past perfect in the first clause. Had you mentioned a period of time up to the beginning of the 21st century, seen from the present day, it might have been appropriate.

1)What about the second question?

2)How could I mention a period of time up to the beginning of the 21st century in the above sentence?

3) Could I still use the past perfect to mean a narration in the more distant past without determining its particular time or duration?