In modern Chinese,
根据地 is overwhelmingly associated with CCP history — the
革命根据地 (revolutionary base areas) were rural strongholds during the 1927-1949 civil war period, including
井冈山 (Jinggangshan),
中央苏区 (Central Soviet Area in Jiangxi), and the post-Long March
延安 (Yan'an). The 'base of operations' meaning extends naturally to business and gangster usage too — '
建立销售根据地' = 'set up a sales stronghold'.