What does 過去へ遡るほど大きいとされる refers to here?


> 華族制度が今なお存在する（成立時期も約300年前と古い）世界。歴史上江戸時代および鎖国が存在せず、西洋文明の普及が早いなどもうひとつの世界との差異は
> **過去へ遡るほど大きいとされる** 。

This is an entry about a fictional parallel world of the novel 'ぼくのご主人様 ' i
understand this as ; from a historical perspective the edo period nor the
sankaku period existed and the differences of ( the original world ) with the
other world is made big as if you went back in time . deepl however translate
this is as : 'differences between the (parallel word ) and the of the world (
the normal one ) are said to be greater the further back in history one goes,
such as the absence of the Edo period and national seclusion, and the rapid
spread of Western civilization' .

So, does 遡るほど大きいとされる mean the further you go back.... ?
<https://ja.wikipedia.org/wiki/%E3%81%BC%E3%81%8F%E3%81%AE%E3%81%94%E4%B8%BB%E4%BA%BA%E6%A7%98!%3F>



  * 差異は過去へ遡るほど大きい is the same as 差異は過去へ遡れば遡るほど大きい. It's a shorter version of the `～ば～ほど` construction. See: [Can 「XければXほどY」 clause pattern be shortened to 「XほどY」?](https://japanese.stackexchange.com/q/243/5010)
  * とされる is the passive version of とする ("to claim", "to consider"), so it's "it is considered that ～" here. See: [What does this としています express?](https://japanese.stackexchange.com/q/56323/5010), [What is the difference between として and とする?](https://japanese.stackexchange.com/q/88737/5010) and [What does として mean here?](https://japanese.stackexchange.com/q/11230/5010)

> 歴史上江戸時代および鎖国が存在せず、西洋文明の普及が早いなどもうひとつの世界との差異は過去へ(遡れば)遡るほど大きいとされる。
>
> As can be seen from the absence of the Edo period and national seclusion,
> and the earlier spread of Western civilization, it is considered that the
> further back in time one goes, the greater the difference from the other
> world becomes.

