Yunzhong (683) — the same event in Old Book of Tang and Zizhi Tongjian

Old Book of Tang: Turkic Gudulu and Yuanzhen besieged the Chanyu Protectorate.; Zizhi Tongjian: In March 683 (Gengyin day), Ashina Gudulu and Ashide…

What each source says

Turkic Gudulu and Yuanzhen besieged the Chanyu Protectorate.

三月庚寅，突厥阿史那骨篤祿、阿史德元珍等圍單于都護府。
Location: 舊唐書卷5 永淳2年 3月

In March 683 (Gengyin day), Ashina Gudulu and Ashide Yuanzhen besiege the Chanyu Protectorate, and capture and kill its Sima Zhang Xingshi.

三月，庚寅，阿史那骨篤祿、阿史德元珍圍單于都護府，執司馬張行師，殺之。
Location: 권203 683년 항

Place: 雲中