Between 1966 and 1967, investigator José Miguel da Costa discovered several of these Punic graves, but all showing evidence of early tomb raiding.

The Roman centres were thought to have been at Praça Tómas Ribeiro, as well as the area around Monte Chaos in Feteira Cima (although little explored archaeologically).

In the fields of Quitéria, Carlos Tavares da Silva and Joaquina Soares (1981) investigated the remains of a 1st-century villa, where the remnants of cobblestone streets and a hypocaust were discovered.

He later preoccupied himself with the coastal defense of the region, establishing the conditions for the construction of Sine's Castle, already protected by elements of the Visigothic wall.

Like Setúbal, but contrary to what happened in Santiago do Cacém or Palmela, the castle was constructed to defend the wealth of the local merchants, indicating a new economic and social order, with the ascension of the bourgeoisie.

[9] During the Portuguese Interregnum and 1383–1385 Crisis, the bourgeoisie and nobles of Sines were one of the municipalities that supported the Master of the Order of Aviz, the later King John I of Portugal in his battle for the throne.

The King, who was careful to indemnity the losses, established a small base of three ships in Sines and Sesimbra to combat these French privateers.

At the end of the 16th century, commanded by Filippo Terzi, in the service of Philip II of Portugal, it was thought that the construction of a new port on Pessegueiro would motivate growth.

In the last decade of the 18th century, the natural anchorage seduced Jacinto Fernandes Bandeira, a merchant, to found Porto Covo, with the hope that his initiative would convince others to establish complementary businesses and a grand port.

In the second half of the 19th century, pyrite from Pias and Moinho dos Paneiros (Sines) and ore from Cercal are transported from the small island.

The establishment of cork and canning industries, small factories producing distillates and artisan goods (bakeries and cobblers), turned the village more attractive to emigrants.

Entrepreneurial growth and republican idealism helped to redevelop the area, as the construction of new roads, the arrival of a rail-line, access to schools and culture became cumulative.

Francisco Luís Lopes' work was an acidic critique of municipal affairs and living conditions that were both sincere and damning, but also flattering and praise-worthy, noting both the villa's problems and its openness and tolerance.

The cork industry, the fishery, some agriculture and tourism marked a period of economic activity that lasted until the end of the 1960s, when, apart from its proximity to the sea, Sines was indistinguishable from other communities in the Alentejo.

In the late 1970s, the arrival of immigrants and refugees from the Portuguese overseas provinces brought new social dynamics, which were later supplemented by foreign workers employed in the port and petrochemical industry.

The municipalities territory is distinguished by three morphological structures: a coastal plain, the residual relief of the Sines Massif, and the eastern escarpment.

Railways serve the cargo traffic and petroleum industry, but there is no more passenger train service; the city's station has been converted into a restaurant.

The Schiller Institute updated its 2014 study on the impact of the Chinese 'New Silk Road' project and considers that the Alentejo port of Sines is a fundamental link for the success of this global initiative.

The port is considered by the world's leading experts in the sector as a key link in the global trade liaison project launched in 2013 by the current paramount leader of the People's Republic of China, in particular for its special and privileged geostrategic position of connecting the continents of Africa and North and South America.

"The Iberian Peninsula is in fact the natural geographical interface of the economic belt of the 'Silk Road', which now stretches from the Pacific to the Atlantic through the land mass of Eurasia, with the 'Silk Sea Route' to the Iberian-American, Caribbean and United States, as well as south towards Africa," says the study of the institute led by Helga and Lindon La Rouche.

According to data released by the AMT - Mobility and Transport Authority - in the first nine months of this year, the port of Sines handled a total of 36.3 million tonnes of goods.