が vs. は in のが/のは...である cleft-sentence structure


The following is a sentence from the Japanese Wikipedia article about Berlin:

> ベルリンという名称が歴史的文書で最も古く遡れるのが1244年である。

I understand the sentence, but I would have expected 遡れるのは here instead of
遡れるのが, just like a prototypical cleft-sentence. Would the variant with のは also
work in this case? If so, how would the nuance be different?

Edit: I should mention that I ask because to my limited knowledge, this が
doesn't really seem to be for exhaustive listing here so that's what has left
me a bit puzzled.




I would use は there.

The current sentence with が sounds as if it was meant to answer a question
about what event characterized the year 1244, rather than stating a fact about
when the name Berlin was first used in historical documents. Since the year
1244 is not mentioned earlier in the article, it sounds odd.

It’s like saying:

> The earliest time the name Berlin can be traced back to in historical
> documents is (none other than that famous) 1244.

The English translation is admittedly awkward but I think you get the idea.

The sentence would have sounded more natural with は in place of が.

* * *

[EDIT]

Maybe I should have explained why the sentence with が sounds the way it does.
I think it is because the listener (reader) interprets only
ベルリンという名称が歴史的文書で最も古く遡れるの as new information and 1244年 as something they are
supposed to already know. The sentence sounds odd because the year 1244 is new
to the listener. The sentence with は, on the other hand, presents the whole
statement as new information.

Let’s look at this with simpler examples.

>   1. こちらが田中さんです。
>

>   2. こちらは田中さんです。
>

When Mr. Tanaka is introduced with the first sentence, the speaker has most
likely talked about him with the listener before. No such prior knowledge on
the listener’s part is assumed in the second sentence.




I would use は there.

The current sentence with が sounds as if it was meant to answer a question
about what event characterized the year 1244, rather than stating a fact about
when the name Berlin was first used in historical documents. Since the year
1244 is not mentioned earlier in the article, it sounds odd.

It’s like saying:

> The earliest time the name Berlin can be traced back to in historical
> documents is (none other than that famous) 1244.

The English translation is admittedly awkward but I think you get the idea.

The sentence would have sounded more natural with は in place of が.

* * *

[EDIT]

Maybe I should have explained why the sentence with が sounds the way it does.
I think it is because the listener (reader) interprets only
ベルリンという名称が歴史的文書で最も古く遡れるの as new information and 1244年 as something they are
supposed to already know. The sentence sounds odd because the year 1244 is new
to the listener. The sentence with は, on the other hand, presents the whole
statement as new information.

Let’s look at this with simpler examples.

>   1. こちらが田中さんです。
>

>   2. こちらは田中さんです。
>

When Mr. Tanaka is introduced with the first sentence, the speaker has most
likely talked about him with the listener before. No such prior knowledge on
the listener’s part is assumed in the second sentence.

