This song contains references to:

1. electronic (1901)
   • “pertaining to electrons” from 1901
2. trip (1959)
   • Falling over, journey and drug reference from 1959.
3. letterbomb (1764)
   • letter c. 1200 + bomb from 1580, or literally delivering an explosive from 1764. In this context it means writing something powerful.
4. drugs (~1400)
   • drug from late 14c
5. polyphonic (1828)
   • “multiplicity of sounds” from 1828, though its greek root could likely be understood much earlier.
6. prostitute (1620)
   • The word is from 1620s, but the meaning is ancient.
7. motors (1450)
   • If in reference to a motorvehicle, then from 1896, though the song could mean abstract motion in general, in which case mid-15c
8. backs to the wall (1918)
   • An idiom for being executed by a firing squad, popularized by Sir Douglas Haig in WWI (1918)

Quick Assessment

From WWI onwards for someone to get all the references, but someone from the early 1800s would understand most of the references.

Modifications

• letterbomb is the most difficult reference, but could be exchanged with a word equaling “large devastating treaty” that should exist at any time in written history.

• electronic is also not really required to preserve the overall meaning of the song, as it only conveys a general sense of synthetic melody (completing the audio synths). One could equate this with a fancy instrument for the time.

• backs to the wall in general conveys a desperate situation, and warfare is not a new invention. A similar more timely phrase could be substituted, though it would require a more timely replacement for “you’re gonna kill us all” too.

Verdict

Stripping the song of its 1900 references would place it in the 1500s, pinned by the general concept of locomotion. Though doing so would remove its psychedelic connotations of drug abuse and withdrawal.