How does it translate noun + ni + shiteitanda?


I was trying to understand this sentence

kimi no senaka o boku wa tayori ni shiteitanda

kimi no senaka = your back boku = I

And I can't figure out what tayori ni shiteitanda means

jisho.org says tayori is a noun, dependence

and that shiteitanda is somehow related to suru
[jisho.org](https://jisho.org/search/%E3%81%97%E3%81%A6%E3%81%84%E3%81%9F%E3%82%93%E3%81%A0)
, if it's a verbal tense of suru I can't find it in the japanese verb
conjugator [japanese verb
conjugator](http://www.japaneseverbconjugator.com/Suru.asp)

Also, this webpage says noun + ni suru (in the case shiteitanda is related to
suru) can be used to "decide on" a noun, ie "I'll go with.." . So may be this
could be something of the form "noun + ni shiteitanda" assuming shiteitanda is
related to suru, and since there is a "noun + ni suru" form but that's as far
as I can guess. How does it translate noun + ni + shiteitanda?




"tayori ni suru" = to rely on

"shiteita" is the past progressive plain form of "suru"

"nda" is a contraction of "no da", which is used to present an explanation or
point out something to the listener.

so in this case, we could interpret it as: "tayori ni shiteitanda" means the
speaker ("boku") is pointing out that they relied on the listener's back
("kimi no senaka").




"tayori ni suru" = to rely on

"shiteita" is the past progressive plain form of "suru"

"nda" is a contraction of "no da", which is used to present an explanation or
point out something to the listener.

so in this case, we could interpret it as: "tayori ni shiteitanda" means the
speaker ("boku") is pointing out that they relied on the listener's back
("kimi no senaka").

