Superstition - In a magic world, believing that what the orcs do has to be unclean. Prior to the French revolution, peasants starved rather than eat potatoes because they came out of the ground and were thus devilish. Maybe the widgets from the union of soviet Dwarves are safe, or maybe they're secretly cursed or in league with demons. Who knows? Did you know that if you spell-fix a crack, you break your mom's back?  Greed - If you have to pay for the rights to use new tech, old tech is just fine. Damn those wizards in arcana city and their copyright protection! It's magic, so maybe there really is a copyright spell limiting the use of magic. Local widget makers ban the use of widgets from foreign countries. Making horse gear and wagons was a huge industry until cars came along and wiped them out. Maybe the state is charging huge taxes (leading to smuggling)? Items are simply too expensive for regular folks to use (think third world countries today)  Pollution - Maybe more magic is seen as contaminating (or really IS contaminating) the land and poisoning the Dryads. The druids are telling everyone the crops will fail if they cast those foreign spells.  Lack of education - Do your peasants read? If priests and nobles don't tell them this stuff, they don't learn it. Make all the incoming merchants only go to trade centers and the spread of knowledge slows.  Power - Oh, no commoner. You can't use that spell. It might let you shoot my soldiers with a magic missile! How did you get the money for that? I guess I need to raise taxes again. But not for your neighbor using good old safe magic.  Terrain - Well, just because the people on the other side of the mountains know stuff doesn't mean it gets here. Then there's the river monsters, not to mention the dragons.  Timeline I can't really tell how much any of this would affect the timeline of technological infiltration - that depends on too many variables.

Superstition 

In a magic world, believing that what the orcs do has to be unclean. Prior to the French revolution, peasants starved rather than eat potatoes because they came out of the ground and were thus devilish. Maybe the widgets from the union of soviet Dwarves are safe, or maybe they're secretly cursed or in league with demons. Who knows? Did you know that if you spell-fix a crack, you break your mom's back? 

Greed 

If you have to pay for the rights to use new tech, old tech is just fine. Damn those wizards in arcana city and their copyright protection! It's magic, so maybe there really is a copyright spell limiting the use of magic. Local widget makers ban the use of widgets from foreign countries. Making horse gear and wagons was a huge industry until cars came along and wiped them out. Maybe the state is charging huge taxes (leading to smuggling)? Items are simply too expensive for regular folks to use (think third world countries today) 

Pollution 

Maybe more magic is seen as contaminating (or really IS contaminating) the land and poisoning the Dryads. The druids are telling everyone the crops will fail if they cast those foreign spells. 

Lack of education 

Do your peasants read? If priests and nobles don't tell them this stuff, they don't learn it. Make all the incoming merchants only go to trade centers and the spread of knowledge slows. 

Power 

Oh, no commoner. You can't use that spell. It might let you shoot my soldiers with a magic missile! How did you get the money for that? I guess I need to raise taxes again. But not for your neighbor using good old safe magic. 

Terrain 

Well, just because the people on the other side of the mountains know stuff doesn't mean it gets here. Then there's the river monsters, not to mention the dragons. 

Timeline 

I can't really tell how much any of this would affect the timeline of technological infiltration - that depends on too many variables.

Superstition - In a magic world, believing that what the orcs do has to be unclean. Prior to the French revolution, peasants starved rather than eat potatoes because the came out of the ground and were thus devilish. Maybe the widgets from the union of soviet Dwarves are safe, or maybe they're secretly cursed or in league with demons. Who knows? Did you know that if you spell-fix a crack, you break your mom's back? Greed - If you have to pay for the rights to use new tech, old tech is just fine. Damn those wizards in arcana city and their copyright protection! It's magic, so maybe there really is a copyright spell limiting the use of magic. Local widget makers ban the use of widgets from foreign countries. Making horse gear and wagons was a huge industry until cars came along and wiped them out. Maybe the state is charging huge taxes (leading to smuggling)? Pollution - Maybe more magic is seen as contaminating (or really IS contaminating) the land and poisoning the Dryads. The druids are telling everyone the crops will fail if they cast those foreign spells. Lack of education - Do your peasants read? If priests and nobles don't tell them this stuff, they don't learn it. Make all the incoming merchants only go to trade centers and the spread of knowledge slows. Power - Oh, no commoner. You can't use that spell. It might let you shoot my soldiers with a magic missile! How did you get the money for that? I guess I need to raise taxes again. But not for your neighbor using good old safe magic.

Superstition - In a magic world, believing that what the orcs do has to be unclean. Prior to the French revolution, peasants starved rather than eat potatoes because they came out of the ground and were thus devilish. Maybe the widgets from the union of soviet Dwarves are safe, or maybe they're secretly cursed or in league with demons. Who knows? Did you know that if you spell-fix a crack, you break your mom's back? Greed - If you have to pay for the rights to use new tech, old tech is just fine. Damn those wizards in arcana city and their copyright protection! It's magic, so maybe there really is a copyright spell limiting the use of magic. Local widget makers ban the use of widgets from foreign countries. Making horse gear and wagons was a huge industry until cars came along and wiped them out. Maybe the state is charging huge taxes (leading to smuggling)? Items are simply too expensive for regular folks to use (think third world countries today) Pollution - Maybe more magic is seen as contaminating (or really IS contaminating) the land and poisoning the Dryads. The druids are telling everyone the crops will fail if they cast those foreign spells. Lack of education - Do your peasants read? If priests and nobles don't tell them this stuff, they don't learn it. Make all the incoming merchants only go to trade centers and the spread of knowledge slows. Power - Oh, no commoner. You can't use that spell. It might let you shoot my soldiers with a magic missile! How did you get the money for that? I guess I need to raise taxes again. But not for your neighbor using good old safe magic. Terrain - Well, just because the people on the other side of the mountains know stuff doesn't mean it gets here. Then there's the river monsters, not to mention the dragons. Timeline I can't really tell how much any of this would affect the timeline of technological infiltration - that depends on too many variables.