So since October much of the trade has been re-routed via other regional ports, mostly in Egypt.
The protests are just the latest chapter in decades of intense tribal and factional infighting driven in part by Sudan’s shifting political alliances under ousted president Omar al-Bashir.
He was deposed in April 2019 after mass protests against his three-decade iron-fisted rule.
Demonstrators say they oppose an October 2020 peace deal between Sudan’s post-Bashir transitional government and rebel groups as “it does not represent” them.
The protests in the east have also triggered unrest in the capital Khartoum, where pro-military demonstrations erupted on Saturday demanding the dissolution of the embattled transitional government.
But for foreign powers who covet Sudan’s Red Sea coast, the region has strategic military dimensions.
It hosted Iranian fleets for decades under Bashir, to the dismay of Tehran’s regional rival Saudi Arabia, whose Red Sea port of Jeddah lies opposite Port Sudan on the other side of the waterway.
And in 2017, Russian president Vladimir Putin and Bashir negotiated the building of a naval base in Port Sudan, to be staffed by up to 300 military and civilian personnel and to include nuclear-powered vessels.
That same year Bashir also signed a 99-year lease for the island of Suakin with Turkish president Recep Tayyip Erdogan, a move that angered Egypt and other rival Sunni Muslim powerhouses worried about Ankara’s spreading regional influence.
The deal provides for building maintenance, docks for ships and renovating Ottoman-era edifices on the island.
Egyptian Pharaoh Ramses II is said to have dubbed Suakin the “white city” as it is home to spectacular buildings made of porous coralline limestone quarried from coral reef.
Suakin is one of many Red Sea islands held by Sudan which analysts see as “integral to the country’s national security”.
The islands cover a total area of 23,100 square kilometres (8,9100 square miles), equivalent to the size of Djibouti, said Shaimaa Abdelsameea, a professor at the Red Sea University.
‘Race for control’
These islands could be used as observation outposts or for conducting military manoeuvres, she noted.
“They are however all uninhabited, making them vulnerable to illicit activities including smuggling,” said Ahmed Abdelaziz, a professor at Port Sudan University.
Sudan had sought to cement its ties with Russia under Bashir to offset the crippling sanctions imposed by Washington against his autocratic regime.
And last year, Moscow announced the signing of a 25-year agreement with Khartoum to build and operate the base in Port Sudan.
However in June, Sudan said it was still “reviewing” the deal after it found that some clauses were “somewhat harmful”.
The move came as Khartoum pushed to solidify ties with the United States following Bashir’s ouster.
In December, Washington removed Khartoum from its crippling State Sponsors of Terrorism list, a designation that had long strangled Sudan’s economy.
The lifting of sanctions took place after a meeting between former US president Donald Trump and prime minister Abdalla Hamdok.
Senior US military officials have since visited Sudan.
“The Red Sea is a key waterway for the movement of American fleets,” according to Abdelsameea.
“It links the US Sixth Fleet in the Mediterranean and the Fifth in the Arabian Gulf,” she said.
“So the race for control over Sudanese ports is very natural.”