Most tanks I've ever had was playing as a China that owned all of Asia and Europe and some of North Africa

(60k tanks)

Most infantry I've ever had was probably 8 million though

I only have reached 20k tank and only 15 mil tropps

I had 10-12m troops as France

I had 46.8k-47.2k tanks as Mongol Empire

No

100k tanks and 400m infantry

No, you didn't

100k tanks I could kind of see

But 400m infantry?

Nope

Yes i did, i joined a late game china that owned india, all of asia russia, all of europe and all of africa , brazil, argentina and colombia and venezula, and all of north america except the western half of the usa

600m infantry was easy it took about 1.5 years. then i started doing the tonks which i got in about 3 yrs