Dragons' Den originally began broadcasting on BBC Two in the United Kingdom.
The British series premiered on BBC Two in January 2005. Its format placed entrepreneurs in front of a panel of investors, who could offer money in return for a share of the business. The early BBC Two broadcasts helped establish the programme before it gained a wider audience.
Dragons' Den later moved to BBC One in 2007. That channel change is the source of a common mix-up: many viewers remember the long-running programme from BBC One and assume it began there. Its original home, however, was BBC Two.
The channel is part of the programme's British broadcast history rather than a description of its format. Other countries have produced their own versions for different networks, so the answer applies specifically to the UK BBC series.