Meaning of ようになり


The problematic part is emboldened.

> 縄文時代は、縄文土器が使用された時代を示す呼称であったが、次第に生活内容を加えた特徴の説明が為される **ようになり**
> 、磨製石器を造る技術、土器の使用、農耕狩猟採集経済、定住化した社会ととらえられるようになった。

I can't understand how does the ようになり function here.

Does it mean "With the gradual increase of the life characteristics, the point
was reached where an explanation got established"?

I know that ようになる can mean "to reach a certain point", but I don't understand
how it works here since it isn't a verb (or is it, and there is an invisible
"masu" ending of some sort?).

I found that なり might be an archaic copula, but it would look weird as the
text is from Wikipedia.




The "i" form of the verb can be used for linking two sentences in the way that
the word "and" works. In your example, using なり, the "i" form of the verb なる.

From Wikipedia, [in the section about the "i" form of Japanese
verbs](https://en.wikipedia.org/wiki/Japanese_verb_conjugation#i_form):

> The i form also has some uses on its own, such as:
>
> ...
>
>   * In conjunctions in formal writing.
>

