Do-Ngoen (blue stone) dzong: Does our history tell us the truth........?

Dechenphodrang monastery at the location
where the do-ngoen dzong was built

I am of not sure if it is true when I read to learn that the Do-ngoen(bule stone) dzong (fortress) was built by Nyoe Gelwa Lhanangpa in the works of Bhutan's history tellers.

More over, it is untrue to my knowledge to claim that do-ngoen dzong as the first ever dzong built in Bhutan, because as far as I know Chelkha dzong (it is in ruins) is said to be the first dzong built in Bhutan by Nyo Gyelwa Lhanangpa.

Who have the right date and justification to support the ascertain that the Do-ngoen dzong was built by Nyo-Gyelwa Lhanangpa. To be precise there should be more appropriate dates supporting one another.

There is this claim in the biography of Phajo that Nyo Lhanangpa had been in conflict with Phajo (I wonder if this would have been so if the biography was self written by Lama Phajo himself), But to the date I found so far has some mathematical contradiction.

Phajo was said to have arrived Bhutan in 1224 AD while Nyo Lhanangpa was said to have died in Tibet in the same year. How do we relate the two, because Nyo Lhanangpa is said to have returned back to Tibet at his later age.

This is where I believe that our history tellers have mistaken the Lhapa Rinchen Gyralpo who was a nephew and a disciple of Nyo Lhanangpa, who reigned the Lhapa kaguye in Bhutan after Lhanangpa entrusted the Chelkha dzong to him while he returned back to Tibet.

Although the dates and histories are not clear, it appears to me that it was Lhapa Rinchen Gyalpo to be precise on who built the Do-ngoen dzong which wasnt big but an average monastery at the location where Dechenphodrang monastery stands.

And most of the history tellers seems to take Lama Lhapa as Nyo Gyelwa Lhanangpa, but in my view Lama Lhapa is a Lam who followed the teaching of Nyo Lhanangpa, because his teaching was later known as Lhapa Kagyue and the followers Lhapa. I don't stand here to say I am right but don't you think there are some loophole that needs a revisit to our history.......?