Much of what is known about Thai cuisine evolved in the Central region. Rice, fish, and vegetables, flavoured with garlic, black pepper, and nam pla (fish sauce), along with an abundance of fresh fruit, comprised the basic diet of Sukhothai. With the rise of Ayutthaya, other elements were added. That now essential ingredient the fiery chilli pepper - was introduced at this time, along with the equally popular coriander, lime and tomato. These may have been brought from their native South America by the Portuguese, who also left a lasting imprint in the form of popular Thai sweets based on egg yolk and sugar. Other influences came from India, Japan, Persia, and especially China.