Complex sentence: Kouber with another part of the Kutrigurs seceded firstly in Pannonia, seemingly recognising the authority of the Avar Khaganate and later, after a unsuccessful attemp to take hold of the Khaganate, resettled in Macedonia.
Split into simpler sentences: Kouber with another part of the Kutrigurs settled in Pannonia, where they seem to have acknowledged the authority of the Avar Khaganate. After a botched attempt to take hold of the Khaganate, they resettled in Macedonia.