Carbon dating of charcoal gathered from a Nok iron smelter at Intime. Nigeria, suggests that iron technology was established there by 410 B.C. This may not be the oldest smelter in sub-Saharan Africa, however. Archaeologists have located evidence of iron-smelting in the Termite Hills of Niger from as early as 1400 B.C.. but skeptics say the wood used for that dating could have already been centuries old when burned as fuel—a problem that dogs carbon dating, especially in arid places like Niger, where wood desiccates and lasts longer. Of course, the same problem could distort dates for the Intime furnace as well, but here there is an important piece of corroborating evidence: Nok pottery found inside the furnace alongside the charcoal.

The author implies which of the following about the "Nok pottery found inside the furnace"?