Complex sentence: Montenegro, a relatively small country but a close ally of Serbia was considered a second class participant; took the invitation to the insistence of Serbia more as a favor, having limited local aspirations over the Sanjak and the north Albanian city of Shkodra.
Split into simpler sentences: Montenegro, a relatively small country but a close ally of Serbia was considered a second class participant. It took the invitation to the insistence of Serbia more as a favour, having limited local aspirations over the Sanjak and the north Albanian city of Shkodra.