Background: Low back pain (LBP) for many years is considered one of the most common conditions causing work absenteeism and long-term disability, with important implications for public health systems and economies. Pain generators of LBP are various, being distinguished specific and non-specific causative mechanisms. The term “non-specific” LBP remains ambiguous as potential sources of pain are supposed to be muscles or joints, but supplementary investigations do not correlate enough to explain the pain intensity and disability. The nociceptive and/or neuropathic mechanisms characteristic for acute pain tend to be influenced by central sensitization while pain chronification occurs, leading to new descriptor as nociplastic pain. Chronic low back pain, considered mostly non-specific, was mechanistically referred to primary musculoskeletal low back pain, the concept introduced in the new ICD-11 classification. The process of acceptance by the scientific medical community raised debates and discussions. The aim of the study was to analyze the evolving concept of non-specific low back pain to chronic primary musculoskeletal low back pain. A narrative literature review was carried out. Conclusions: The term non-specific low back pain is used when the pain generators have not been accurately determined or cannot fully explain the existing symptomatology. Chronic primary musculoskeletal low back pain is better explained by central sensitization mechanisms and altered nociception, named nociplastic pain. Because of raised ambiguities regarding this concept further studies are expected to shed light on the problem.