Complex sentence: The causes of these movements were both economic and political, which intensified after 1860, when the political factor facing the predominant role in departures to outside, as a result of deteriorating relations with the Spanish metropolis.
Split into simpler sentences: The causes of these movements were both economic and political. The problem intensified after 1860, when the political factor facing the predominant role in departures to outside, as a result of deteriorating relations with the Spanish metropolis.