Complex sentence: Malinowski carefully traced the network of exchanges of bracelets and necklaces across the Trobriand Islands, and established that they were part of a system of exchange (the Kula ring), and that this exchange system was clearly linked to political authority.
Split into simpler sentences: Malinowski carefully traced the network of exchanges of bracelets and necklaces across the Trobriand Islands, and established that they were part of a system of exchange (the Kula ring). He stated that this exchange system was clearly linked to political authority.