当時 (とうじ)at that time; in those days

当時, its kanji, and other words that share them.Open this graph

Kanji in 当時

当初とうしょbeginning; start
当局とうきょくauthorities; relevant authorities
当選とうせんbeing elected
当面とうめんcurrent; urgent
担当たんとうbeing in charge (of an area of responsibility); being responsible (for a work role, etc.)
本当ほんとうtruth; reality
当然とうぜんnatural; right
担当者たんとうしゃperson in charge (of an area of work); person responsible
一時いちじone o'clock
同時どうじsimultaneous; concurrent
時事じじevents of the day; current affairs
時代じだいperiod; epoch
時半じはんhalf past (the hour)
時期じきtime; season
時間じかんtime
臨時りんじtemporary; provisional

See how 当時 connects to the rest of Japanese.