The first Irishman, and Irish missionary, to have visited China would seem to be the Friar known as ‘James of Ireland’ who accompanied his fellow Franciscan, Odoric of Pordenone (1286-1331), on his travels around the world.
Odoric set out for China in 1318 and went via Constantinople, Armenia, Persia, Baghdad and India. Whether James was with him from the start or joined him along the way, we do not know, but James was with Oderic when he left India for China by way of Sumatra. They landed at Guangzhou and went on to Quanzhou, Hangzhou and Beijing where they spent three years. They were not the first Franciscans there and were able to stay in houses of their Order along the way. They returned to Italy in 1329 and the story of their travels attracted widespread attention. James outlived Odoric and probably had many good stories to tell.
Where he came from in Ireland, how he got to Italy and what he felt in China, we do not know though his willingness to travel and be part of an adventure are typical of the Irish tradition. If anyone can shed further light on James, please come forward!