Between 1500 and 1800, the volume of water flowing through the IJssel decreased, decreasing the importance of Deventer's harbour.
The competition with trade centres in Holland, as well as the religious war between 1568 and 1648, brought a decline in the city's economy.

In the 18th century, the iron industry came to Deventer.
East of the town, so-called "oer", riversand containing iron, was found as early as 900.
From this material, ore was produced and brought to town.
The main road of the villages Okkenbroek, Lettele and Schalkhaar is still named Oerdijk (Ore Dyke).
Between 1500 and 1800, the volume of water flowing through the IJssel decreased, decreasing the importance of Deventer's harbour. The competition with trade centres in Holland, as well as the religious war between 1568 and 1648, brought a decline in the city's economy.
In the 18th century, the iron industry came to Deventer. East of the town, so-called "oer", riversand containing iron, was found as early as 900. From this material, ore was produced and brought to town. The main road of the villages Okkenbroek, Lettele and Schalkhaar is still named Oerdijk (Ore Dyke).
Deventer