Of course they led the world. Have you never heard the name of Khalid bin Walid or Omar or Osman or Ali. They ruled one- half part of the world.
No they didn't. The Islamic empire, at its peak, covered 8.73% of the land mass of the world. That's less than *deep breath*, the Second French Colonial Empire, the Yuan Dynasty, the Qing Dynasy, the Spanish Empire, the Russian Empire, the Mongol Empire and the British Empire.
Why are Muslim apologists so allergic to facts?
Khalid ibn al-Waleed (learn how to spell his name ffs) may have been a gifted military commander, but he's hardly unparalleled. Alexander the Great, Napoleon Bonaparte, Genghis Khan, to name a few, were all indisputably greater. And what about those other Rashidun? Omar was remarkable only in his barbarity (I still laugh at his catchphrase, "A'adhribu 3unuqah?!", "Shall I behead him, rasoolullah?!"), the rest were quite unremarkable.