Complex sentence: When he reached Macau, the persecution of European missionaries delayed his onward journey so he used his time there to learn Chinese before proceeding to Hangzhou in June 1621 and to Beijing in late 1623.
Split into simpler sentences: When he reached Macau, the persecution of European missionaries prevented him from proceeding. He used his time there to learn Chinese before proceeding to Hangzhou in June 1621 and on to Beijing in late 1623.