At the end of Legion, the titan Sargeras was imprisoned, but not before he plunged his sword into the planet Azeroth. This not only devastated a massive area (much of the desert zone of Silithus is now cracked and scorched), but badly wounded the gestating titan inside. While the heroes managed to ablate the worst of the damage (at the cost of the majority of their artifact weapons' mythic power), the world is still wounded and bleeding a substance called "Azerite," which has great magical potential. The Horde Warchief, Sylvanas Windrunner, attempts to consolidate Horde power on Kalimdor and gain a monopoly on Azerite (which is primarily found at the southern end of the continent). Her campaign to do so, the War of Thorns, formed a pre-launch event for the expansion and ends with the major Night Elf holdings on the continent seized or (in the case of their capital city of Darnassus) annihilated. The Alliance makes a retaliatory strike against her home base, the Undercity, which was formerly the human capital of Lordaeron. This succeeds in driving the Horde out, but before leaving Sylvanas saturates the area with disease and toxins that render it uninhabitable. With this tit-for-tat military exchange, the Horde has almost complete control over Kalimdor, while the Alliance has near-total dominion over the Eastern Kingdoms. With further conflict inevitable, Battle for Azeroth takes the two factions to the continents of Kul Tiras and Zandalar to recruit new allies in order to turn the tides of war.
Now, on the other part of the equation, the items that return materials on mission finished are overlooked. Looking at this Wowhead comment https://www.wowhead.com/item=162114/crimson-ink-well#comments:id=2607578 the most lucrative ones are the disenchanting rod (returns enchanting mats, best case scenario, 10x veiled crystals) and the magnetic mining pick (returns ores, up to 40x Stormsilver). This is totally server dependant, but you will need to check which ones are worth where you play.
Guide to Obtaining and Selling the WoW Token Buying and selling the WoW Token, which allows players to buy game time with gold, or make extra gold by selling the token on the Auction House. What is Blizzard (Battle.net) Balance Overview of Blizzard (Battle.net) Balance, a currency used to buy Blizzard Entertainment products including World of Warcraft character services. How to Purchase World of Warcraft Game Time The cost of a WoW game time subscription, how to acquire a subscription, gift one, and cancel it, as well as how to play WoW for free.