I think I could take a few things back 1,000 years and introduce them based on what I know.
- Basic steam power.
- Crop rotation.
- Antiseptic and rudimentary first aid.
- Water purification.
Take into account one basic thing, 1,000 years ago people drank beer and fermented beverages because water made people sick. Basic filtration and boiling alone would make water potable which wasn’t common 1,000 years ago.
God gave the Israelites Crop Rotation and the rule for letting the land “rest” one in every seven years.
The Romans had all the necessary technology for a steam locomotive and a rail road.