Complex sentence: After his death the Empire fell apart into feudal anarchy and the Empress Consort Helena continued to govern Serres area from 1356, but already in 1365 she was ousted by Despot Jovan Uglješa Mrnjavčević, who forged a tiny but powerful mini-state in Serres.
Split into simpler sentences: After his death his Empire fell into feudal anarchy and the Empress Consort Helena continued to govern Serres area from 1356. In 1365 she was ousted by Despot Jovan Uglješa Mrnjavčević, who forged a tiny but powerful mini-state in Serres.