Chittagong (Xatigan in Portuguese), the second largest city and main port of Bangladesh, was home to a thriving trading post of the Portuguese Empire in the 16th and 17th centuries. The Portuguese first arrived in Chittagong around 1528 and left in 1666 after the Mughal conquest. It was the first European colonial enclave in the historic region of Bengal.

Chittagong was the largest seaport in the Sultanate of Bengal, which was termed as the "Shahi Bangalah" (Imperial Bengal) in Persian and Bengali. The Portuguese referred to the port city as Porto Grande de Bengala, which meant "the Grand Harbor of Bengal". The term was often simplified as Porto Grande.

On 9 May 1512, a fleet of four ships commanded by João da Silveira from the Estado da India arrived in Chittagong from Goa. They were followed by several embassies from the Kingdom of Portugal to the Sultanate of Bengal, then reputed as the wealthiest region in the Indian subcontinent. He set up the first Portuguese factory in Bengal at Chittagong in 1517. Traders from Portuguese Malacca, Bombay and Ceylon also frequented the region.

Some sources indicate that Joao Coelho had arrived in Chittagong before João da Silveira. Many Malaccan Portuguese had come to the Bengal before Silveira in Moorish ships as traders. Moreover, some of the Portuguese settled in Pipli (present day Orissa) in 1514 and had visited Western Bengal.

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