The world in 28 AD — what happened that year

6 events the sources record for this year, grouped by region.

What happened

Guangwu visited Qiao and ordered Ma Wu and Wang Ba to besiege Liu Hong at Suihe. (Book of the Later Han (Hou Hanshu), Annals 後漢書卷1上光武帝紀上建武4年)
Zhu You surrounded Qin Feng at Liqiu; Guangwu went to Liqiu in the twelfth month. (Book of the Later Han (Hou Hanshu), Annals 後漢書卷1上光武帝紀上建武4年)
When a governor of Liaodong of Han came with troops, he held Wina-am fortress firmly for several dozen days and sent carp to suggest there was water. (Samguk Sagi (History of the Three Kingdoms) 卷14 大武神王 11年) tradition
In the eleventh month, while Emperor Guangwu was in Wan, Zan Peng attacked Chen Feng for three years and beheaded ninety thousand. In the twelfth month he reached Liqiu and tried to persuade Chen Feng, who refused. Zhu You besieged Liqiu in place of Zan Peng, while Zan Peng attacked Tian Rong. (Zizhi Tongjian (Comprehensive Mirror) 資治通鑑卷041 (원문 단락 #3033, 28년))

Across the Rhine, the Frisii break the peace, provoked by Roman greed (Tacitus, Annals and Histories Ann. 4.72)
The governor of Lower Germany, Apronius, summons troops from the upper provinces to respond to the Frisii (Tacitus, Annals and Histories Ann. 4.73)