The Bandidos bikie gang - best known for its role in the infamous Milperra massacre in 1984 - has swallowed up another Perth gang to establish a presence in WA.
Sunday's "patching over" of the Rock Machine gang comes a month after the Finks were taken over by the notorious Mongols following weeks of negotiations.
But police said the changes to the bikie landscape in WA did not necessarily heighten the threat of violence.
In 1984, the Bandidos were involved in a carpark shoot-out in Milperra, NSW, with the Comancheros bikie gang, which has had a foothold in WA since 2009.
Four Comancheros and two Bandidos were shot dead during the battle. The seventh victim was a female bystander aged 14.
"That was a long time ago," said Acting Det-Insp. Jeff Christmass from the WA Police gang crime squad.
"I don't see that being an issue in WA now."
The Bandidos' Australian gang formed in 1983 after some bikies split from the Comancheros and incinerated the gang's "colours" during a ceremony.
Soon after setting up in WA in 2009, the Rock Machine became embroiled in a "war" with the Rebels - Australia's biggest bikie gang - which included the shooting in 2011 of Rebels WA president Nick Martin, who survived the murder attempt.
The war was triggered by the defection of a former Rebels member to the Rock Machine and also resulted in firebombings.
Earlier this year, the Rock Machine's sergeant-at-arms was released on parole after serving a year behind bars for attempted extortion.
It is understood the man had left the Rock Machine before the Bandidos patched them over.
"This is not a strengthening of a gang in WA," Acting Det-Insp. Christmass said.
"It's pretty well the same people wearing a different patch. As always, we will monitor them."
_The West Australian _revealed the existence of the Rock Machine in 2009, after a tip-off that about 20 recruits were holding meetings at a Kardinya industrial unit which had been fitted out as a gym.
Police said some recruits were men with an axe to grind against some of Perth's existing gangs.
At the time the gang was boasting its move to WA was part of the "great Australian takeover" by the Rock Machine, which started in Canada and was involved in a long and bloody war with the Hells Angels that resulted in 162 deaths.
Since yesterday, the Bandidos website has been featuring messages of congratulations from around the world to the "probationary chapter" in WA.
"Fat welcome Bandidos West Coast . . . into our Bandido nation," one overseas member posted.