The title "House of Israel" was first used in reference to the united kingdom of Israel. Later, during the divided kingdom, the northern tribes retained the title "house of Israel," while the southern tribes of Judah and Benjamin became known as the "House of Judah." Afterward, the divided House of Israel was sent into captivity and became known as, "the lost sheep of the House of Israel. This begs the question, "Was the House of Israel lost  physically or spiritually?"

Later, during New Testament times, "Yeshua sent these twelve out, and commanded them, saying, “Do not go among the nations, and do not enter into any city of the Samaritans. Rather, go to the lost sheep of the house of Israel" (Matt. 10:5-6). The fact that Yeshua sent His apostles to the "lost sheep of the house of Israel" proves that both He and the apostles knew where the lost sheep were located at the time, meaning that they weren't lost in a physical sense, but in a spiritual sense. Notice what Elohim said through the prophet Jeremiah on the topic of lost sheep: "My people have been lost sheep. Their shepherds have caused them to go astray; they have turned them away on the mountains; they have gone from mountain to hill; they have forgotten their resting place" (Jer. 50:6).  The statement, "Their shepherds have caused them to go astray..." proves that they were lost spiritually.

A short time after that, Yeshua declared, "...I was not sent but to the lost sheep of the house of Israel" (Matt. 15:24). The fact that Yeshua spent most of His ministry in Judea proves that He was referring to the united House of Israel, which included the House of Judah, because they were lost spiritually. Finally, in 70 AD, the House of Judah was dispersed among the nations, just as Israel had been scattered before them.

Some argue that the reason why Yeshua's ministry included Judea is because a number, if not all, of the house of Israel were located in Judea at the time, and that Yeshua knew who they were. There are two things wrong with this theory. First, if the house of Israel were located in Judea at the time, than Yeshua would not have said, "...I was not sent but to the LOST sheep of the house of Israel"(Matt. 15:24). Second, the inclusion of the word "but" in Yeshua's statement means that God sent Him exclusively to the lost sheep of the house of Israel. Of course, the Good News accounts contain many occurrences when Yeshua preached directly to the Jews and called them to repentance. As a result, if the house of Judah was not part of the lost sheep of the house of Israel at the time, than Yeshua disobeyed His Father.

So your acknowledging that Yeshua went to the Jews and preached directly to them and called them to repentance, and that that would not be disobeying His Father who commanded Him not to go to anyone BUT the lost sheep of the house of Israel?