Leaving Lisbon in April 1657, Martini, Dorville and 17 other Jesuits (among whom Ferdinand Verbiest) arrived in Macau on 17 July 1658, after a long and arduous journey during which several lost their life.
Grueber was sent to Rome in order to defend Jesuit astronomer Adam Schall against the accusation of 'fostering superstitious practices' (motivated by his working on the Chinese calendar).
As traveling over the seas was increasingly difficult and unsafe - the Portuguese were losing their trade monopoly at the hands of the Dutch - they decided to attempt an exploratory overland journey that, if successful could bring China closer to Europe too.
Leaving Beijing on 13 April 1661 Grueber and Dorville entered Tibet 13 July and spent two months (October and November) in its capital Lhasa.
From there they descended into the basin of the Ganges river, entered India (8 February) and visited Patna, and Benares before arriving finally in Agra (31 March), the former capital of the Mughal empire.