history of the Shōwa period (1926-1989)
Refers to the historical study or narrative of Japan's Shōwa era, often covering political, social, and cultural developments.
I'm taking a course on the history of the Shōwa period at university.
This book provides a clear overview of Shōwa-era history.
日本史 is the broader history of Japan, while 昭和史 focuses only on the Shōwa period.
Compound of 昭和 (Shōwa, the era name) and 史 (history).