noun
pre-Taika period
Historical term referring to the period in the 6th and 7th centuries before the Taika Reform (645 CE). Used in academic or historical contexts.
大化前代の政治体制について研究している。
I am researching the political system of the pre-Taika period.
The Taika Reform itself, the event that marks the end of the 大化前代 period.
From 大化 (Taika, the era name of the reform) + 前代 (previous era). The exact historical derivation is straightforward; the term is a modern historiographical label.