Definition: Rewrite each original sentence in order to make it easier to understand by non-native speakers of English. You can do so by replacing complex words with simpler synonyms (i.e. paraphrasing), deleting unimportant information (i.e. compression), and/or splitting a long complex sentence into several simpler ones. The final simplified sentences need to be grammatical, fluent, and retain the main ideas of their original counterparts without altering their meanings.
Input: Progress in developing the TAR was hindered by political and economic obstacles throughout the 1960s, 1970s and early 1980s.

The advance in making the TAR was slowed by political and economic issues from the 1960's through the early 1980's.