Dark-silvery Rock

People in parts of western Africa and southwestern Asia were the first to realize that the dark-silvery rocks poking out of the earth could be worked into tools and weapons, sometime around 1500 B.C., evidence shows. The metal was probably discovered there [blank] accident when some ore was dropped into a fire and cooled into wrought iron, historians think. The eureka moment didn't reach Europe for [blank] 500 years, traveling slowly north and west through Greece, Italy, central Europe and finally to the British Isles [blank] the spread of the famous Celtic tribes. The Celts diffused iron technology over much of the continent through warfare, where their victory was assured due to the strength of iron weapons. Perhaps not the most peaceful of cultural exchanges, but where the technology did travel, it caught on fast. Iron [blank] life a lot easier in those days, when just living to the age of 45 was a feat. By that time, much of Europe had settled into small village life, [blank] the soil with bronze and stone tools. Iron farming tools, such as sickles and plough tips, made the process more efficient and allowed farmers to [blank] tougher soils, try new crops and have more time for other activities.