A radiative hydrodynamic simulation for a typical , powerful high redshift radio galaxy is presented . The jet is injected at one third the speed of light into a 10000 times denser , homogeneous medium . In the beginning of the simulation , the bow shock consists of a spherical shell that is similar to a spherical blast wave . This shell cools radiatively down to \approx 10 ^ { 4 } K , providing after 6 \times 10 ^ { 6 } yrs a neutral column of 3.8 \times 10 ^ { 21 } \mathrm { cm } ^ { -2 } around the whole system . The shell starts to fragment and forms condensations . This absorbing screen will cover a smaller and smaller fraction of the radio source , and therefore the emission line region , and eventually form stars in typically 10 ^ { 4 } globular clusters of 10 ^ { 6 } \mathrm { M } _ { \odot } . Approximately 10 ^ { 9 } \mathrm { M } _ { \odot } are entrained into the radio cocoon . This gas , cooling and illuminated from the radio source , could be the emission line gas observed in high redshifted radio galaxies and radio loud quasars . The neutral column behind the bow shock can account for the absorption found in almost all of the small sources . The globular cluster excess of \approx 10 ^ { 4 } systems found in present day brightest cluster galaxies ( BCGs ) , which are believed to be the vestiges of these objects , is consistent with the presented scenario .