I believe that the reason these old world technologies were erased from history are so the elite upper class could control us, the population of the earth. Nikola Tesla famously stated that understanding the universe requires thinking in terms of energy, frequency, and vibration. He believed all matter consists of resonant frequencies and that human consciousness and reality can be influenced by adjusting internal vibrational energy, often linked to the numbers 3, 6, and 9.
Tesla had a way to provide FREE energy to the world! The Wardenclyffe Tower, or "Tesla Tower," was a 1901–1917 project on Long Island designed by Nikola Tesla to provide free, wireless electricity and communication globally. It was built to transmit power through the Earth and air using resonance. The project failed and was demolished for scrap due to financial issues and lack of funding. When J.P. Morgan found out that he could not profit by providing free energy, he withdrew his support for the wireless power project.
You may also want to look into Royal Raymond Rife. Rife frequencies are specific electromagnetic frequencies, often in the low-energy radiofrequency range (<25x10⁶ Hz), hypothesized by Royal Raymond Rife in the 1920s to treat various diseases. Rife claimed that pathogenic organisms have a "mortal oscillatory rate" and that transmitting these specific frequencies into the body can destroy pathogens and cure illnesses, including cancer. I have a Rife Frequency machine that I have been using for a few years to aid in my diabetes management. The medical industrial complex also could not profit from this technology as they would rather sell you their big pharma products.
Rockefeller and Rothschild families were and are primary resistance to these old world technologies.