Cheraman Juma Masjid of India is the oldest mosque in India which was built in 629, during the life time of Prophet Muhammad (PBUH). The mosque was built by the first known Indian Muslim named Cheraman Perumal Bhaskara Ravi Varma.
Cheraman Perumal Bhaskara was among the last kings of the area who accepted Islam which helped the spread of Islam in this area. Today around 27% of the population is muslim.
Arab Traders were in contact with Indian merchants even before Islam, after Arabs accepted Islam they started preaching it among Indian merchants which created the first first muslim community in India. This also counters the false allegations that Islam spread in India through force.
Muhammad bin Qasim invaded India after muslim women were abducted in 711, while the first muslim community was established around 82 years before the first muslim expedition in the region.