Coal has been mined in the region since ancient times but became more widespread in the 13th and 14th centuries. Among those to profit from coal were the Bishops of Durham and merchants of Newcastle.

As a sea port, Newcastle could benefit from the trade because shallow coal seams lay close to the Tyne. Ports like Hartlepool and Stockton lay outside the coalfield and Sunderland coal lay deep underground. Nevertheless Newcastle merchants still had to contend with the development of rival Tyneside ports.

The earliest reference to Durham coal is in the Boldon Book of 1183 which records a coal miner at Escomb. Coal was often called 'Sea Coal' in medieval Durham because it was washed up on local beaches, but inland 'Sea coal' was mined at a few places such as Hett near Spennymoor where coal mining was recorded in 1298. The Prince Bishops owned rights to mining coal and lead in Durham but in 1303 the Bishop gave lesser landowners the right to mine their land. Durham monks exploited coal from at least the 14th century and in the 1350s owned or leased mines at Lumley, Rainton and Ferryhill. The first record of coal mining beneath the level of free drainage in Durham was at Moorhouse near Rainton where monks of Finchale provided a water pump for a mine Medieval mines were usually shallow bell pits, dug down from the surface and then outwards into the coal seam in the shape of a bell. Coal and miners were hoisted up and down in the manner of a bucket in a well. Mine roofs only collapsed if the 'colliers' burrowed too far outwards. This may be what caused deaths in coal mines at Whickham and Thrislington in 1329. Another source of danger were candles used for lighting the mines. The explosion of coal gas was a major hazard.

In 1286 Newcastle was the leading English port for exporting leather aquired from local livestock. The border wars that ravaged the countryside destroyed this trade, but coal was already beginning to dominate. In 1291, 80 quarters of coal were sent to Corfe Castle in Dorset from Newcastle and coal was shipped to London from at least 1305. Newcastle's walls were falling into decay but still protected the town from the marauding Scots and enabled trade to continue. Newcastle was the fourth wealthiest town in England by 1334 after London, Bristol and York and the eleventh largest in 1372 with 2,637 tax payers.

Early coal mines supplying coal to Newcastle existed at Elswick, Winlaton, Heworth and on the Town Moor. By 1378 Newcastle shipped 15,000 tons of coal per year and exported coal to many parts of Europe as well as importing iron ore from Sweden. In 1452 trades included the Keelmen who ferried the coal to collier ships in the centre of the Tyne. The phrase Coals to Newcastle' describing an unnecessary pursuit was first recorded in 1538 Newcastle was the most important medieval port in the region and this was demonstrated by the establishment of the Society of Masters and Mariners of Newcastle at Trinity House in 1492. Their jurisdiction covered every single port and creek from Whitby to Holy Island. Shipping and shipbuilding were important at Newcastle and the town was building ships from at least 1296 when a galley was completed for King Edward's fleet.

Gateshead belonged to the Bishops of Durham and was often claimed by the Newcastle merchants as their own. In 1334 King Edward banned Newcastle's mayor and bailiffs from mooring ships here and in 1344 the Bishop of Durham prosecuted Newcastle merchants for wrecking his quays at Gateshead and Whickham. Disputes over the Tyne Bridge were another problem. In 1415 the Bishop obtained a suit from the King's Court recovering his third of the bridge taken from him by the Newcastle mayor. The problem was that the Bishops did not always maintain their side of the bridge and this was damaging Newcastle's trade. Newcastle would not succeed in annexing Gateshead until the sixteenth century.

Germanus of Tynemouth Priory created a port at North Shields in 1225. It traded peacefully until 1267 when Newcastle merchants attacked the inhabitants and seized a ship. Newcastle saw the port as a threat and in 1292 gained support from Edward I, who ordered the dismantling of the North Shields jetties. The king objected because part of Newcastle's revenue belonged to him while the North Shields revenue belonged entirely to the Priors. In 1303 Edward III banned markets, fairs and the unloading and loading of ships by the Tynemouth Priors. In 1258 the Newcastle merchants persuaded the Priors of Durham not to develop port facilities at South Shields and in 1303 Edward III banned loading and uloading of ships here by the Durham priors.

North Shields fishing port facilities were banned in 1303 and re-established in 1390 but trading in coal and other commodities remained illegal. By 1429 there were 14 fish quays and 200 houses at North Shields where fishermen ventured as far as Iceland in boats and cobles. Coal trading was restored to North Shields in 1446 and Tynemouth Priory could ship coal without reference to Newcastle, but it was banned in 1530 and once again restricted to Newcastle.

Sunderland more usually known in Medieval times as Wearmouth received a charter from Hugh Pudsey the Bishop of Durham in 1179 giving its merchants the same rights as Newcastle, but Sunderland never really developed as a Medieval port. This was due to the geological difficulties of developing a port in the Wear gorge and the fact that the Wearside coal was deep and inaccessible. Nevertheless Sunderland was shipping cargoes of coal to Whitby Abbey in 1396 and ships were built here from 1346.

Associated with coal mining was Iron mining, an important medieval trade recorded at Muggleswick in Durham in 1298. Most iron was made by heating iron ore in simple blast furnaces called Bloomeries using charcoal made from wood acquired from the extensive Medieval forests. Coal was not normally used because its sulphur content caused the iron to be brittle. In 1306 a petition was handed to parliament against the Bishop of Durham. It accused him of destroying the Weardale forests for the extraction of charcoal and establishment of iron bloomeries.

Salt making was another early industry closely connected with coal mining. In 1290 Robert de Brus, granted permission to John Rumundebi to make salt at Hart near Hartlepool and in the following century large quantities of salt were traded at nearby Cowpen and Greatham. South Shields became the most important salt making centre in the region from around 1448. Salt making involved heating huge quantities of seawater brine in large salt pans using coal.