Instead of using a BGP network command to add routes to the BGP table, the enterprise BGP routers can instead redistribute routes from an IGP into BGP. The end goals are the same:
Inject the public address range, but not the private IP address range, into the BGP table.
Advertise one route for the public address range, instead of any individual subnets of the range.
The enterprise routers that run BGP often already run the IGP as well and have learned routes for either the entire public range as one route or ...